diff --git a/.github/FUNDING.yml b/.github/FUNDING.yml
deleted file mode 100644
index 8e103359..00000000
--- a/.github/FUNDING.yml
+++ /dev/null
@@ -1,12 +0,0 @@
-# These are supported funding model platforms
-
-github: [angular-package] # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
-patreon: sciborrudnicki # Replace with a single Patreon username
-open_collective: # Replace with a single Open Collective username
-ko_fi: # Replace with a single Ko-fi username
-tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
-community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
-liberapay: # Replace with a single Liberapay username
-issuehunt: # Replace with a single IssueHunt username
-otechie: # Replace with a single Otechie username
-custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']
diff --git a/.gitignore b/.gitignore
deleted file mode 100644
index 7e4e96c8..00000000
--- a/.gitignore
+++ /dev/null
@@ -1,133 +0,0 @@
-# See http://help.github.com/ignore-files/ for more about ignoring files.
-
-# compiled output
-/dist
-/tmp
-/out-tsc
-# Only exists if Bazel was run
-/bazel-out
-
-# profiling files
-chrome-profiler-events*.json
-speed-measure-plugin*.json
-
-# IDEs and editors
-/.idea
-.project
-.classpath
-.c9/
-*.launch
-.settings/
-*.sublime-workspace
-
-# IDE - VSCode
-.vscode/*
-!.vscode/settings.json
-!.vscode/tasks.json
-!.vscode/launch.json
-!.vscode/extensions.json
-.history/*
-
-# misc
-/.sass-cache
-/connect.lock
-
-# Logs
-/libpeerconnection.log
-logs
-*.log
-npm-debug.log*
-testem.log
-yarn-debug.log*
-yarn-error.log*
-
-# Runtime data
-pids
-*.pid
-*.seed
-*.pid.lock
-
-# Directory for instrumented libs generated by jscoverage/JSCover
-lib-cov
-
-# Coverage directory used by tools like istanbul
-coverage
-
-# nyc test coverage
-.nyc_output
-
-# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
-.grunt
-
-# Bower dependency directory (https://bower.io/)
-bower_components
-
-# node-waf configuration
-.lock-wscript
-
-# Compiled binary addons (https://nodejs.org/api/addons.html)
-build/Release
-
-# Dependency directories
-node_modules/
-jspm_packages/
-
-# TypeScript v1 declaration files
-typings/
-
-# Optional npm cache directory
-.npm
-
-# Optional eslint cache
-.eslintcache
-
-# Optional REPL history
-.node_repl_history
-
-# Output of 'npm pack'
-*.tgz
-
-# Yarn Integrity file
-.yarn-integrity
-
-# dotenv environment variables file
-.env
-
-# parcel-bundler cache (https://parceljs.org/)
-.cache
-
-# next.js build output
-.next
-
-# nuxt.js build output
-.nuxt
-
-# vuepress build output
-.vuepress/dist
-
-# Serverless directories
-.serverless/
-
-# FuseBox cache
-.fusebox/
-
-#DynamoDB Local files 
-.dynamodb/ 
-
-# OS generated files
-Thumbs.db
-.DS_Store
-
-# Ignored files
-/.vscode/*
-*.code-workspace
-!.vscode/tasks.json
-build
-dist
-graphics
-fonts
-*.ignore*
-
-# demos
-demo
-
diff --git a/CHANGELOG.md b/CHANGELOG.md
deleted file mode 100644
index bcb84eac..00000000
--- a/CHANGELOG.md
+++ /dev/null
@@ -1,132 +0,0 @@
-# Change Log
-
-All notable changes to this project will be documented in this file.
-
-The format is based on [Keep a Changelog](http://keepachangelog.com/)
-and this project adheres to [Semantic Versioning](http://semver.org/).
-
-## [5.0.0] - 2022-01-30
-
-### [5.0.0] Added
-
-- Added `Undefined` generic type.
-- Added guard function `guardStringLengthBetween()`. [53e02d8]
-- Added check function `isStringLengthBetween()`. [5d044f9]
-- Added generic type `GenericObject`. [fd14947]
-- Added `guardStringIncludes()` and `guardStringIncludesSome()` functions with tests. [691f07e]
-- Added `guardObjectKeysIn()` function to guard the value to be an `object` with specified keys in it(or its prototype chain). [21e523b]
-- Added `are` prefixed functions to check the values of a rest parameter. `areBigInt()` `areBoolean()` `areDate()` `areDefined()` `areFalse()` `areNull()` `areNumber()` `areRegExp()` `areSymbol()` `areTrue()` `areUndefined()`. [823dac3]
-- Added a generic type `MinMax` that takes generic type variable `Min` and `Max` that represents the range between minimum and maximum. [e503d38]
-- Added new guard functions `guardDate()`, `guardFalse()`, `guardNumberBetween()`, `guardObjectKeyIn()`, `guardObjectSomeKeys()`, `guardRegExp()`, `guardStringLength()`, `guardTrue()`. [c374612]
-- Added `isObjectKeysIn()`, `isObjectSomeKeys()`, `isStringIncludes()` and `isStringIncludesSome()` and to the `is` object and to the `Is` interface.  [55635fa] [1e48fb1] [a4cb61d] [f809f32] [5c85a03] [d440e38] [0efe8ae]
-- Added `CallbackPayload` and `ForEachCallback` types. [98a2722]
-- Added the `type` object consists of `are`, `is` and `guard` objects. [dfb3df9]
-- Added an object to handle executing the tests. [8dd8099] [230063b]
-- Added `recognizeValue()` to recognize type of any value. [d2f756e]
-
-[53e02d8]: https://github.com/angular-package/type/commit/53e02d8fdf33ef9c2a66615be19c22eb3a606b12
-[5d044f9]: https://github.com/angular-package/type/commit/5d044f9a8a5dce0c3e79f6858b0e29a81cf3f3d5
-[fd14947]: https://github.com/angular-package/type/commit/fd1494735a7ddf6653919448b67984cbb341bbdc
-[691f07e]: https://github.com/angular-package/type/commit/691f07e2cf31eb3a52923715ef091f86a181a15f
-[21e523b]: https://github.com/angular-package/type/commit/21e523b3a46e3e8243276e5008de72ea9b3c3756
-[0efe8ae]: https://github.com/angular-package/type/commit/0efe8aed83d03313921176206636bc8b0730d188
-[d440e38]: https://github.com/angular-package/type/commit/d440e388f6f853c01ef9aab620c206f2233bd3cf
-[5c85a03]: https://github.com/angular-package/type/commit/5c85a03a7fd34dd64a650597f48cea9968940f68
-[f809f32]: https://github.com/angular-package/type/commit/f809f32cddd2c53568d60f0af6e57b941d50fa87
-[a4cb61d]: https://github.com/angular-package/type/commit/a4cb61d5b8bfd7f1ac548842d355a045266f6e7b
-[1e48fb1]: https://github.com/angular-package/type/commit/1e48fb1448b908f09cc2628063eff457d920a903
-[823dac3]: https://github.com/angular-package/type/commit/823dac3b62288c1016e8244fc741939bdc140d89
-[e503d38]: https://github.com/angular-package/type/commit/e503d3885d560274e1f30e763e04c526a8548317
-[c374612]: https://github.com/angular-package/type/commit/c374612e96d14c6d23449e03535283e5e1614765
-[55635fa]: https://github.com/angular-package/type/commit/55635fad55a8f0e14486246215cf7f22b9f1ab26
-[98a2722]: https://github.com/angular-package/type/commit/98a2722ea64ccb476942b606239dd001457d7e03
-[230063b]: https://github.com/angular-package/type/commit/230063ba135022fdcbbb65fc3569f248f836adbf
-[8dd8099]: https://github.com/angular-package/type/commit/8dd80991ba9e5950970880d8aa449c1c7a143699
-[dfb3df9]: https://github.com/angular-package/type/commit/dfb3df9f82116cd2737031b255f0aad62e4c1fa8
-[d2f756e]: https://github.com/angular-package/type/commit/d2f756e1498b531836aaac08a9c01b512cdaba2c
-
-### [5.0.0] Changed
-
-- Updated the way of checking values in some of the `is` and `isNot` prefixed functions.
-- Updated `isPrimitive()` and `isType()` function does not use switch on the `type` argument.
-- Updated `guard`, `is`, `isNot` prefixed functions to use updated generic type `ResultCallback` with `payload` parameter of generic type variable `Payload`.
-- Updated `isStringLength()` function to check the specific `length`. [061ab52]
-- Updated `guardStringLength()` function to check the specific `length`. [0e48591]
-- Updated `is {}` object by adding `stringLengthBetween` method. [083ffd0]
-- Updated `guardIs` object by adding `objectKeysIn`, `stringIncludes`, `stringLengthBetween` and `stringIncludesSome` methods. [8679b4c] [1d44d2e]
-- Updated `GuardIs` interface by adding `stringLengthBetween`. [7387e23]
-- Updated `areString()` function that works by using the returned methods. [68c9365]
-- Freeze the `guard`, `guardIs`, `isNot` and `is` object. [00e8841] [09fb70f] [c4e6f8f] [0efe8ae]
-- Updated `isObject()` function by adding the ability to check any kind of object, not only the `Object`. [de6aa12]
-- Updated `NumberBetween` interface by adding `MinMax` interface and a generic type variable `Type`. [1263a2e]
-- Updated `StringOfLength` interface by adding `MinMax` interface and a generic type variable `Type`. [24621f7]
-- Updated `isInstance()` function can now check any kind of instance. [7d288c2]
-- Updated `Is` interface by adding `stringLengthBetween`. [26d7a9d] [8ddb720]
-- Updated `Is` interface and `isNot` by changing the function types to the `typeof` operator. [8ddb720] [8ddb720]
-- Updated the type of callback function `ResultCallback` to provide the type of value and the shape of `payload`. [8ddb720] [34a1b1f]
-- Updated functions by adding a generic type variable `Payload` constrained by the `object` type that is by default equal to the `object`. [5c9486f]
-- Updated functions by adding a `payload` parameter of generic type ~~`CallbackPayload`~~ that takes generic type variable `Payload` to assign to callback function `payload` parameter. [6d190f5]
-- Updated functions by removing `typeOf()` function if it's not necessary to use it. [8ddb720]
-- Updated the `Defined` to not use of `Never` type cause of some compile issues. [e09a84f]
-- Updated the `guard` object by removing `is` property. [aa80250]
-- Updated the `isParam()` function by removing the `Func` generic type in favor of `Function`. [42065c9]
-- Updated `isObjectKey()`, `isObjectKeyIn` to check only one key instead of multiple keys. [b7092a9]
-- Updated `isObjectKeys()` works differently, now it searches for every key. The previous functionality provides `isObjectSomeKeys()`. [b7092a9]
-
-[0e48591]: https://github.com/angular-package/type/commit/0e485914cc410509efed0bcfa40d29c456fc9b32
-[061ab52]: https://github.com/angular-package/type/commit/061ab521e29b046549f169d5c7ebdd5f8f9f24b6
-[26d7a9d]: https://github.com/angular-package/type/commit/26d7a9d2dc5fd84e5715ccea679bf2412f57c45a
-[1d44d2e]: https://github.com/angular-package/type/commit/1d44d2eb3f69ca372486037bad06aa2feb59419f
-[083ffd0]: https://github.com/angular-package/type/commit/083ffd06832a2381dac4755f0b206eb81d8cc25a
-[8679b4c]: https://github.com/angular-package/type/commit/8679b4c5845880a3be41d6d72dd115a7f4d99be2
-[7387e23]: https://github.com/angular-package/type/commit/7387e2342b7c02ccf64f8cb980cd8b801e333ca9
-[68c9365]: https://github.com/angular-package/type/commit/68c93656d4b3cd1c5158bc6021059929e54860ab
-[0efe8ae]: https://github.com/angular-package/type/commit/0efe8aed83d03313921176206636bc8b0730d188
-[c4e6f8f]: https://github.com/angular-package/type/commit/c4e6f8f033364b24fd864b77ab62c7de70d7c265
-[09fb70f]: https://github.com/angular-package/type/commit/09fb70f87634923dce1fd979da30a8041a7f9922
-[00e8841]: https://github.com/angular-package/type/commit/00e8841cc63430ee6423232ee804196fee9cbfd5
-[de6aa12]: https://github.com/angular-package/type/commit/de6aa127ec3f0821487448d784d390edc35fb289
-[1263a2e]: https://github.com/angular-package/type/commit/1263a2e92f6722dd9d025f5c5eef0e1ba652fe66
-[24621f7]: https://github.com/angular-package/type/commit/24621f7b421392226e939161989b28ae0898524f
-[7d288c2]: https://github.com/angular-package/type/commit/7d288c2290055a164259f6e5ea336bec8938bf66
-[34a1b1f]: https://github.com/angular-package/type/commit/34a1b1fc0fac8b9044d3c4da96d9dc642f388507
-[5c9486f]: https://github.com/angular-package/type/commit/5c9486f859a4e61476c220f228bf1cb34511e319
-[6d190f5]: https://github.com/angular-package/type/commit/6d190f5ef1d425b272ca65954e5a9780f561d3c6
-[e09a84f]: https://github.com/angular-package/type/commit/e09a84fc1ea2109c4c480743e3b749325a1d9c5f
-[aa80250]: https://github.com/angular-package/type/commit/aa80250dec231e10dc11d14c7b86e88c2297e82b
-[42065c9]: https://github.com/angular-package/type/commit/42065c9f7aa938e2d514ff9bfc9b197463a9bbda
-[b7092a9]: https://github.com/angular-package/type/commit/b7092a9766c5706ba2c7ba5670a96553f1ad4bd0
-
-### [5.0.0] Removed
-
-- Removed `guard` prefixed function types. [a8e8566]
-- Removed `Func` type in favor of build-in `Function` type. [8ddb720] [5148f05]
-- Removed `Key` type in favor of build-in `PropertyKey` type. [562ec13]
-- Removed `CycleHook` type. [4d53a55]
-
-[a8e8566]: https://github.com/angular-package/type/commit/a8e856663f8c57c3c89271c1c1948ecdc96b01d1
-[8ddb720]: https://github.com/angular-package/type/commit/8ddb720a071dc97ccfdda8757f911aac1a6ec9bd
-[5148f05]: https://github.com/angular-package/type/commit/5148f059722ee8979d8cf1945f80d8e65290bb0d
-[562ec13]: https://github.com/angular-package/type/commit/562ec1396f61bb8b1c7363097a5e8b9a2e4392bc
-[4d53a55]: https://github.com/angular-package/type/commit/4d53a55a6b26d8a20678ae3dc39544e24cd3d9fa
-
-## [4.2.0] - 2021-06-25
-  
-### Added
-
-* [`a6b567f`](https://github.com/angular-package/type/commit/a6b567f32a00726d2b7ecf38ce7a57a42366aaf6)  
-  New `NumberBetween` and `StringOfLength` type.
-
-* [`21f3f48`](https://github.com/angular-package/type/commit/21f3f48029d79e1dfd4507d3a684ec1e81e44713)  
-  New functions `isDate()`, `isFalse()`, `isNumberBetween()`, `isRegExp()`, `isStringLength()`, `isTrue()` with tests and types.
-
-* [`7d4cda7`](https://github.com/angular-package/type/commit/7d4cda7d3c91fca89a35baed6c1db9cd35070f4e)  
-  This `CHANGELOG.md`.
-
-### Changed
-
-* [`e70b034`](https://github.com/angular-package/type/commit/e70b034934b81b3af6ab1976153cbbad8c148f78)  
-  All types description in the `README.md`.
-
-* [`61e9376`](https://github.com/angular-package/type/commit/61e93766fab7d72cafa70da712f296c6ca6e9304)  
-  Add possibility to use `is` prefixed functions directly from the `guard` eg. `guard.array()`.
diff --git a/LICENSE b/LICENSE
deleted file mode 100644
index 5c0c2913..00000000
--- a/LICENSE
+++ /dev/null
@@ -1,21 +0,0 @@
-MIT License
-
-Copyright (c) 2021 angular-package
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
diff --git a/README.md b/README.md
deleted file mode 100644
index 01f2026a..00000000
--- a/README.md
+++ /dev/null
@@ -1,681 +0,0 @@
-# angular-package
-
-<img align="left" width="100" height="100" src="https://avatars.githubusercontent.com/u/31412194?s=400&u=c9929aa36826318ccac8f7b84516e1ce3af7e21c&v=4" />
-
-The angular-package supports the development process of [angular][angulario]-based applications in varied ways through the thoughtful, reusable, easy-to-use small pieces of code called packages.
-
-[**docs.angular-package.dev**](https://docs.angular-package.dev)
-
-<br>
-
-## Packages
-
-| Package                                      | Description                                                       | Status |
-| :------------------------------------------- | :---------------------------------------------------------------- | -----: |
-| [callback][callback-github-readme]           | Manages the callback [`function`][js-function].                   | [![npm version][callback-npm-badge-png]][callback-npm-badge] |
-| [change-detection][cd-github-readme]         | Improves application performance.                                 | [![npm version][cd-npm-badge-png]][cd-npm-badge] |
-| [component-loader][cl-github-readme]         | Handles dynamic loading components.                               | [![npm version][cl-npm-badge-png]][cl-npm-badge] |
-| [core][core-github-readme]                   | Core features.                                                    | [![npm version][core-npm-badge-png]][core-npm-badge] |
-| [error][error-github-readme]                 | Manages an [`Error`][js-error].                                   | [![npm version][error-npm-badge-png]][error-npm-badge] |
-| [name][name-github-readme]                   | The name with prefix and suffix.                                  | [![npm version][name-npm-badge-png]][name-npm-badge] |
-| [preferences][preferences-github-readme]     | Preferences, settings, options, configuration and setup in steps. | [![npm version][preferences-npm-badge-png]][preferences-npm-badge] |
-| [prism][prism-github-readme]                 | [`Prism`][prism-js] highlighter module.                           | [![npm version][prism-npm-badge-png]][prism-npm-badge] |
-| [property][property-github-readme]           | Handles object properties.                                        | [![npm version][property-npm-badge-png]][property-npm-badge] |
-| [range][range-github-readme]                 | The range between a minimum and maximum.                          | [![npm version][range-npm-badge-png]][range-npm-badge] |
-| [reactive][reactive-github-readme]           | Automatize the process of creating some rxjs features.            | [![npm version][reactive-npm-badge-png]][reactive-npm-badge] |
-| [storage][storage-github-readme]             | The storage of data under allowed names.                          | [![npm version][storage-npm-badge-png]][storage-npm-badge] |
-| [tag][tag-github-readme]                     | Any tag with optional attributes.                                 | [![npm version][tag-npm-badge-png]][tag-npm-badge] |
-| [testing][testing-github-readme]             | Support for testing other packages.                               | [![npm version][testing-npm-badge-png]][testing-npm-badge] |
-| [text][text-github-readme]                   | Text on the template with replaceable tags.                       | [![npm version][text-npm-badge-png]][text-npm-badge] |
-| **[type][type-github-readme]**               | **Common types, type guards, and type checkers.**                 | [![npm version][type-npm-badge-png]][type-npm-badge] |
-| [ui][ui-github-readme]                       | User interface.                                                   | *In Progress* |
-| [wrapper][wrapper-github-readme]             | Wrap the text with the opening and closing chars.                 | [![npm version][wrapper-npm-badge-png]][wrapper-npm-badge] |
-
-Click on the package name to visit its [GitHub](https://github.com/) page.
-
-<br>
-
-## angular-package/type
-
-Common types, type guards and type checkers.
-
-[![Gitter][gitter-badge]][gitter-chat]
-[![Discord][discord-badge]][discord-channel]
-[![Twitter][twitter-badge]][twitter-follow]
-<!-- npm badge -->
-[![npm version][type-npm-badge-svg]][type-npm-badge]
-<!-- GitHub badges -->
-[![GitHub issues][type-badge-issues]][type-issues]
-[![GitHub forks][type-badge-forks]][type-forks]
-[![GitHub stars][type-badge-stars]][type-stars]
-[![GitHub license][type-badge-license]][type-license]
-<!-- Sponsors badges -->
-[![GitHub sponsors][github-badge-sponsor]][github-sponsor-link]
-[![Support me on Patreon][patreon-badge]][patreon-link]
-
-<br>
-
-## Documentation
-
-For the detailed documentation go to [**https://type.angular-package.dev/**](https://type.angular-package.dev/)
-
-## Table of contents
-
-* [Basic concepts](#basic-concepts)
-* [Skeleton](#skeleton)
-* [Installation](#installation)
-* [Api](#api)
-* [Changelog](#changelog)
-* [Git](#git)
-  * [Commit](#commit)
-  * [Versioning](#versioning)
-* [License](#license)
-
-<br>
-
-## Basic concepts
-
-Checks
-> It's to check the provided value to be **the same** as **expected**.
-
-Type guard (constrain)
-> Constrains the parameter type to **not let** input **unexpected** value in the **code editor**.
-
-Guards
-> It's a **combination** of both above, **constrains** the type of the parameter in the **code editor**, and checks its provided argument.
-
-Defines
-> Returns defined value from a method of an object.  
-> Defines new value in an object and returns a defined value.  
-
-Gets
-> Returns a value from an object.
-
-Sets
-> Adds or updates an element with a specified key and a value to an object and returns an object.  
-
-<br>
-
-## Skeleton
-
-This package was generated by the [library skeleton][skeleton] with [Angular CLI](https://github.com/angular/angular-cli) version 13.0.0.
-
-Copy this package to the `packages/type` folder of the [library skeleton][skeleton] then run the commands below.
-
-<br>
-
-## Code scaffolding
-
-Run `ng generate component component-name --project type` to generate a new component. You can also use `ng generate directive|pipe|service|class|guard|interface|enum|module --project type`.
-> Note: Don't forget to add `--project type` or else it will be added to the default project in your `angular.json` file.
-
-### Build
-
-Run `ng build type` to build the project. The build artifacts will be stored in the `dist/` directory.
-
-### Publishing
-
-After building your library with `ng build type`, go to the dist folder `cd dist/type` and run `npm publish`.
-
-### Running unit tests
-
-Install `@angular-package/type` with command:
-
-```typescript
-npm i @angular-package/testing --no-save
-```
-
-Run `ng test type` to execute the unit tests via [Karma](https://karma-runner.github.io).
-
-### Further help
-
-To get more help on the Angular CLI use `ng help` or go check out the [Angular CLI Overview and Command Reference](https://angular.io/cli) page.
-
-<br>
-
-## Installation
-
-Install `@angular-package/type` package with command:
-
-```bash
-npm i @angular-package/type --save
-```
-
-<br>
-
-## Api
-
-```typescript
-// Main.
-import {
-  recognizeValue, // From the `5.0.0` version
-  typeOf,
-} from '@angular-package/type';
-```
-
-```typescript
-// `are` prefix functions.
-import {
-  // Function.
-  areBigInt, // From the `5.0.0` version
-  areBoolean, // From the `5.0.0` version
-  areDate, // From the `5.0.0` version
-  areDefined, // From the `5.0.0` version
-  areFalse, // From the `5.0.0` version
-  areNull, // From the `5.0.0` version
-  areNumber, // From the `5.0.0` version
-  areRegExp, // From the `5.0.0` version
-  areString,
-  areSymbol, // From the `5.0.0` version
-  areTrue, // From the `5.0.0` version
-  areUndefined, // From the `5.0.0` version
-} from '@angular-package/type';
-```
-
-```typescript
-// `guard` prefix functions.
-import { 
-  guardArray,
-  guardBigInt,
-  guardBoolean,
-  guardClass,
-  guardDate, // From the 5.0.0 version
-  guardDefined,
-  guardFalse, // From the 5.0.0 version
-  guardFunction,
-  guardInstance,
-  guardKey,
-  guardNull,
-  guardNumber,
-  guardNumberBetween, // From the 5.0.0 version
-  guardObject,
-  guardObjectKey,
-  guardObjectKeyIn, // From the 5.0.0 version
-  guardObjectKeys,
-  guardObjectKeysIn, // From the 5.0.0 version
-  guardObjectSomeKeys, // From the 5.0.0 version
-  guardPrimitive,
-  guardRegExp, // From the 5.0.0 version
-  guardString,
-  guardStringIncludes, // From the 5.0.0 version
-  guardStringIncludesSome, // From the 5.0.0 version
-  guardStringLength, // From the 5.0.0 version
-  guardStringLengthBetween, // From the 5.0.0 version
-  guardSymbol,
-  guardTrue, // From the 5.0.0 version
-  guardType,
-  guardUndefined,
-} from '@angular-package/type'; 
-```
-
-```typescript
-// `is` prefix functions.
-import {
-  isArray,
-  isBigInt,
-  isBoolean,
-  isBooleanObject,
-  isBooleanType,
-  isClass,
-  isDate, // From the 4.2.0 version.
-  isDefined,
-  isFalse, // From the 4.2.0 version.
-  isFunction,
-  isInstance,
-  isKey,
-  isNull,
-  isNumber,
-  isNumberBetween, // From the 4.2.0 version.
-  isNumberObject,
-  isNumberType,
-  isObject,
-  isObjectKey,
-  isObjectKeyIn,
-  isObjectKeys,
-  isObjectKeysIn, // From the 5.0.0 version
-  isObjectSomeKeys, // From the 5.0.0 version
-  isParam,
-  isPrimitive,
-  isRegExp, // From the 4.2.0 version.
-  isString,
-  isStringIncludes, // From the 5.0.0 version
-  isStringIncludesSome, // From the 5.0.0 version
-  isStringLength, // From the 4.2.0 version.
-  isStringLengthBetween, // From the 5.0.0 version
-  isStringObject,
-  isStringType,
-  isSymbol,
-  isTrue, // From the 4.2.0 version.
-  isType,
-  isUndefined,
-} from '@angular-package/type';
-```
-
-```typescript
-// `isNot` prefix functions.
-import {
-  isNotBoolean,
-  isNotDefined,
-  isNotFunction,
-  isNotNull,
-  isNotNumber,
-  isNotString,
-  isNotUndefined
-} from '@angular-package/type';
-```
-
-```typescript
-// Objects.
-import { are, guard, is, isNot, type } from '@angular-package/type';
-```
-
-```typescript
-// Interfaces.
-import {
-  MinMax
-} from '@angular-package/type';
-```
-
-```typescript
-// Types.
-import {
-  AnyBoolean,
-  AnyNumber,
-  AnyString,
-  CallbackPayload, // From the `5.0.0` version.
-  Constructor,
-  Defined,
-  ForEachCallback,  // From the `5.0.0` version.
-  Never,
-  NotUndefined,
-  NumberBetween, // From the `4.2.0` version.
-  Primitive,
-  Primitives,
-  ResultCallback, // From the `4.2.0` version
-  StringOfLength, // From the `4.2.0` version.
-  Type,
-  Types,
-  Undefined
-} from '@angular-package/type';
-```
-
-<br>
-
-## Changelog
-
-The **changelog** of this package is based on [*keep a changelog*](https://keepachangelog.com/en/1.0.0/). To read it, click on the [CHANGELOG.md][type-github-changelog] link.
-
-> A changelog is a file which contains a curated, chronologically ordered list of notable changes for each version of a project. - [*keep a changelog*](https://keepachangelog.com/en/1.0.0/)
-
-<br>
-
-## GIT
-
-### Commit
-
-* [AngularJS Git Commit Message Conventions][git-commit-angular]
-* [Karma Git Commit Msg][git-commit-karma]
-* [Conventional Commits][git-commit-conventional]
-
-### Versioning
-
-[Semantic Versioning 2.0.0][git-semver]
-
-**Given a version number MAJOR.MINOR.PATCH, increment the:**
-
-* MAJOR version when you make incompatible API changes,
-* MINOR version when you add functionality in a backwards-compatible manner, and
-* PATCH version when you make backwards-compatible bug fixes.
-
-Additional labels for pre-release and build metadata are available as extensions to the MAJOR.MINOR.PATCH format.
-
-**FAQ**
-How should I deal with revisions in the 0.y.z initial development phase?
->The simplest thing to do is start your initial development release at 0.1.0 and then increment the minor version for each subsequent release.
-
-How do I know when to release 1.0.0?
-
->If your software is being used in production, it should probably already be 1.0.0. If you have a stable API on which users have come to depend, you should be 1.0.0. If you’re worrying a lot about backwards compatibility, you should probably already be 1.0.0.
-
-## License
-
-MIT © angular-package ([license][type-license])
-
-<!-- Funding -->
-[github-badge-sponsor]: https://img.shields.io/static/v1?label=Sponsor&message=%E2%9D%A4&logo=GitHub&link=https://github.com/sponsors/angular-package
-[github-sponsor-link]: https://github.com/sponsors/angular-package
-[patreon-badge]: https://img.shields.io/endpoint.svg?url=https%3A%2F%2Fshieldsio-patreon.vercel.app%2Fapi%3Fusername%3Dsciborrudnicki%26type%3Dpatrons&style=flat
-[patreon-link]: https://patreon.com/sciborrudnicki
-
-[angulario]: https://angular.io
-[skeleton]: https://github.com/angular-package/skeleton
-
-<!-- Update status -->
-[experimental]: https://img.shields.io/badge/-experimental-orange
-[fix]: https://img.shields.io/badge/-fix-red
-[new]: https://img.shields.io/badge/-new-green
-[update]: https://img.shields.io/badge/-update-red
-
-<!-- Discord -->
-[discord-badge]: https://img.shields.io/discord/925168966098386944
-[discord-channel]: https://discord.com/channels/925168966098386944/925168966098386948
-
-<!-- Gitter -->
-[gitter-badge]: https://badges.gitter.im/angularpackage/Lobby.svg
-[gitter-chat]: https://gitter.im/angularpackage/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge
-
-<!-- Twitter -->
-[twitter-badge]: https://img.shields.io/twitter/url?style=social&label=Follow%20%40angularpackage&url=https%3A%2F%2Ftwitter.com%2Fangularpackage
-[twitter-follow]: https://twitter.com/angularpackage
-
-<!-- GIT -->
-[git-semver]: http://semver.org/
-
-<!-- GIT: commit -->
-[git-commit-angular]: https://gist.github.com/stephenparish/9941e89d80e2bc58a153
-[git-commit-karma]: http://karma-runner.github.io/0.10/dev/git-commit-msg.html
-[git-commit-conventional]: https://www.conventionalcommits.org/en/v1.0.0/
-
-<!-- This package: type -->
-  <!-- GitHub: badges -->
-  [type-badge-issues]: https://img.shields.io/github/issues/angular-package/type
-  [type-badge-forks]: https://img.shields.io/github/forks/angular-package/type
-  [type-badge-stars]: https://img.shields.io/github/stars/angular-package/type
-  [type-badge-license]: https://img.shields.io/github/license/angular-package/type
-  <!-- GitHub: badges links -->
-  [type-issues]: https://github.com/angular-package/type/issues
-  [type-forks]: https://github.com/angular-package/type/network
-  [type-license]: https://github.com/angular-package/type/blob/master/LICENSE
-  [type-stars]: https://github.com/angular-package/type/stargazers
-  <!-- This package -->
-  [type-github-changelog]: https://github.com/angular-package/type/blob/main/CHANGELOG.md
-
-<!-- Package: callback -->
-  <!-- npm -->
-  [callback-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fcallback.svg
-  [callback-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fcallback.png
-  [callback-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fcallback
-  [callback-npm-readme]: https://www.npmjs.com/package/@angular-package/callback#readme
-
-  <!-- GitHub -->
-  [callback-github-readme]: https://github.com/angular-package/callback#readme
-
-  [package-callback-callbackpayload]: https://github.com/angular-package/callback#callbackpayload
-  [package-callback-resultcallback]: https://github.com/angular-package/callback#resultcallback
-
-<!-- Package: change-detection -->
-  <!-- npm -->
-  [cd-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fchange-detection.svg
-  [cd-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fchange-detection.png
-  [cd-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fchange-detection
-  [cd-npm-readme]: https://www.npmjs.com/package/@angular-package/change-detection#readme
-
-  <!-- GitHub -->
-  [cd-github-readme]: https://github.com/angular-package/change-detection#readme
-
-<!-- Package: component-loader -->
-  <!-- npm -->
-  [cl-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fcomponent-loader.svg
-  [cl-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fcomponent-loader.png
-  [cl-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fcomponent-loader
-  [cl-npm-readme]: https://www.npmjs.com/package/@angular-package/component-loader#readme
-
-  <!-- GitHub -->
-  [cl-github-readme]: https://github.com/angular-package/component-loader#readme
-
-<!-- Package: core -->
-  <!-- npm -->
-  [core-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fcore.svg
-  [core-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fcore.png
-  [core-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fcore
-  [core-npm-readme]: https://www.npmjs.com/package/@angular-package/core#readme
-
-  <!-- GitHub -->
-  [core-github-readme]: https://github.com/angular-package/core#readme
-
-<!-- Package: error -->
-  <!-- npm -->
-  [error-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Ferror.svg
-  [error-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Ferror.png
-  [error-npm-badge]: https://badge.fury.io/js/%40angular-package%2Ferror
-  [error-npm-readme]: https://www.npmjs.com/package/@angular-package/error#readme
-
-  <!-- GitHub -->
-  [error-github-readme]: https://github.com/angular-package/error#readme
-
-<!-- Package: name -->
-  <!-- npm -->
-  [name-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fname.svg
-  [name-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fname.png
-  [name-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fname
-  [name-npm-readme]: https://www.npmjs.com/package/@angular-package/name#readme
-
-  <!-- GitHub -->
-  [name-github-readme]: https://github.com/angular-package/name#readme
-
-<!-- Package: preferences -->
-  <!-- npm -->
-  [preferences-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fpreferences.svg
-  [preferences-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fpreferences.png
-  [preferences-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fpreferences
-  [preferences-npm-readme]: https://www.npmjs.com/package/@angular-package/preferences#readme
-
-  <!-- GitHub -->
-  [preferences-github-readme]: https://github.com/angular-package/preferences#readme
-
-<!-- Package: prism -->
-  <!-- npm -->
-  [prism-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fprism.svg
-  [prism-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fprism.png
-  [prism-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fprism
-  [prism-npm-readme]: https://www.npmjs.com/package/@angular-package/prism#readme
-
-  <!-- GitHub -->
-  [prism-github-readme]: https://github.com/angular-package/prism#readme
-
-<!-- Package: property -->
-  <!-- npm -->
-  [property-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fproperty.svg
-  [property-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fproperty.png
-  [property-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fproperty
-  [property-npm-readme]: https://www.npmjs.com/package/@angular-package/property#readme
-
-  <!-- GitHub -->
-  [property-github-readme]: https://github.com/angular-package/property#readme
-
-<!-- Package: range -->
-  <!-- npm -->
-  [range-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Frange.svg
-  [range-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Frange.png
-  [range-npm-badge]: https://badge.fury.io/js/%40angular-package%2Frange
-  [range-npm-readme]: https://www.npmjs.com/package/@angular-package/range#readme
-
-  <!-- GitHub -->
-  [range-github-readme]: https://github.com/angular-package/range#readme
-
-<!-- Package: reactive -->
-  <!-- npm -->
-  [reactive-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Freactive.svg
-  [reactive-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Freactive.png
-  [reactive-npm-badge]: https://badge.fury.io/js/%40angular-package%2Freactive
-  [reactive-npm-readme]: https://www.npmjs.com/package/@angular-package/reactive#readme
-
-  <!-- GitHub -->
-  [reactive-github-readme]: https://github.com/angular-package/reactive#readme
-
-<!-- Package: storage -->
-  <!-- npm -->
-  [storage-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fstorage.svg
-  [storage-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fstorage.png
-  [storage-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fstorage
-  [storage-npm-readme]: https://www.npmjs.com/package/@angular-package/storage#readme
-
-  <!-- GitHub -->
-  [storage-github-readme]: https://github.com/angular-package/storage#readme
-
-<!-- Package: tag -->
-  <!-- npm -->
-  [tag-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Ftag.svg
-  [tag-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Ftag.png
-  [tag-npm-badge]: https://badge.fury.io/js/%40angular-package%2Ftag
-  [tag-npm-readme]: https://www.npmjs.com/package/@angular-package/tag#readme
-
-  <!-- GitHub -->
-  [tag-github-readme]: https://github.com/angular-package/tag#readme
-
-<!-- Package: testing -->
-  <!-- npm -->
-  [testing-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Ftesting.svg
-  [testing-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Ftesting.png
-  [testing-npm-badge]: https://badge.fury.io/js/%40angular-package%2Ftesting
-  [testing-npm-readme]: https://www.npmjs.com/package/@angular-package/testing#readme
-
-  <!-- GitHub -->
-  [testing-github-readme]: https://github.com/angular-package/testing#readme
-
-<!-- Package: text -->
-  <!-- npm -->
-  [text-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Ftext.svg
-  [text-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Ftext.png
-  [text-npm-badge]: https://badge.fury.io/js/%40angular-package%2Ftext
-  [text-npm-readme]: https://www.npmjs.com/package/@angular-package/text#readme
-
-  <!-- GitHub -->
-  [text-github-readme]: https://github.com/angular-package/text#readme
-
-<!-- Package: type -->
-  <!-- npm -->
-  [type-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Ftype.svg
-  [type-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Ftype.png
-  [type-npm-badge]: https://badge.fury.io/js/%40angular-package%2Ftype
-  [type-npm-readme]: https://www.npmjs.com/package/@angular-package/type#readme
-
-  <!-- GitHub -->
-  [type-github-readme]: https://github.com/angular-package/type#readme
-
-<!-- Package: ui -->
-  <!-- npm -->
-  [ui-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fui.svg
-  [ui-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fui.svg
-  [ui-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fui
-  [ui-npm-readme]: https://www.npmjs.com/package/@angular-package/ui#readme
-
-  <!-- GitHub -->
-  [ui-github-readme]: https://github.com/angular-package/ui#readme
-
-<!-- Package: wrapper -->
-  <!-- npm -->
-  [wrapper-npm-badge-svg]: https://badge.fury.io/js/%40angular-package%2Fwrapper.svg
-  [wrapper-npm-badge-png]: https://badge.fury.io/js/%40angular-package%2Fwrapper.png
-  [wrapper-npm-badge]: https://badge.fury.io/js/%40angular-package%2Fwrapper
-  [wrapper-npm-readme]: https://www.npmjs.com/package/@angular-package/wrapper#readme
-
-  <!-- GitHub -->
-  [wrapper-github-readme]: https://github.com/angular-package/wrapper#readme
-
-<!-- Angular -->
-[angular-component-factory-resolver]: https://angular.io/api/core/ComponentFactoryResolver
-[angular-view-container-ref]: https://angular.io/api/core/ViewContainerRef
-[angular-component-ref]: https://angular.io/api/core/ComponentRef
-
-<!-- Angular -->
-[angular-component-factory-resolver]: https://angular.io/api/core/ComponentFactoryResolver
-[angular-view-container-ref]: https://angular.io/api/core/ViewContainerRef
-
-<!-- Jasmine -->
-[jasmine-describe]: https://jasmine.github.io/api/3.8/global.html#describe
-[jasmine-expect]: https://jasmine.github.io/api/3.8/global.html#expect
-[jasmine-it]: https://jasmine.github.io/api/3.8/global.html#it
-[jasmine-matchers]: https://jasmine.github.io/api/3.9/matchers.html
-
-<!-- Javascript  -->
-[js-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
-[js-array-every]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every
-[js-array-some]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some
-
-[js-bigint]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt
-[js-bigintconstructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt/BigInt
-[js-boolean]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean
-[js-booleanconstructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean/Boolean
-
-[js-classes]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes
-
-[js-date]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date
-
-[js-error]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error
-
-[js-function]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions
-
-[js-getter]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/get
-
-[js-hasownproperty]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwnProperty
-
-[js-instanceof]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof
-[js-in-operator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/in
-[js-isarray]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
-[js-isfinite]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isFinite
-[js-isfrozen]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/isFrozen
-[js-isnan]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN
-
-[js-map]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map
-
-[js-null]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/null
-[js-number]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number
-[js-numberconstructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/Number
-[js-numberisfinite]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isFinite
-[js-numberisinteger]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isInteger
-[js-numberisnan]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN
-[js-numberissafeinteger]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger
-
-[js-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
-[js-object-define-property]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty
-[js-object-getownpropertydescriptor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptor
-[js-object-getOwnpropertydescriptors]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptors
-
-[js-primitive]: https://developer.mozilla.org/en-US/docs/Glossary/Primitive
-[js-promise]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise
-
-[js-rangeerror]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RangeError
-[js-referenceerror]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ReferenceError
-[js-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp
-[js-rest-parameter]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/rest_parameters
-
-[js-set]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set
-[js-setter]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/set
-[js-static]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/static
-[js-storage]: https://developer.mozilla.org/en-US/docs/Web/API/Storage
-[js-string]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String
-[js-stringconstructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/String
-[js-symbol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol
-[js-symbolconstructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/Symbol
-[js-syntaxerror]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SyntaxError
-
-[js-tostring]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toString
-[js-typeerror]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError
-[js-typeof]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof
-
-[js-undefined]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/undefined
-[js-urlerror]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/URIError
-
-[js-weakset]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet
-
-<!-- Karma -->
-[karma]: http://karma-runner.github.io/0.10/index.html
-
-<!-- Prism -->
-[prism-js]: https://prismjs.com/
-
-<!-- Typescript -->
-[ts-any]: https://www.typescriptlang.org/docs/handbook/basic-types.html#any
-[ts-boolean]: https://www.typescriptlang.org/docs/handbook/basic-types.html#boolean
-[ts-classes]: https://www.typescriptlang.org/docs/handbook/2/classes.html
-[ts-enums]: https://www.typescriptlang.org/docs/handbook/enums.html
-[ts-function]: https://www.typescriptlang.org/docs/handbook/2/functions.html
-[ts-interface]: https://www.typescriptlang.org/docs/handbook/interfaces.html#our-first-interface
-[ts-never]: https://www.typescriptlang.org/docs/handbook/basic-types.html#never
-[ts-null]: https://www.typescriptlang.org/docs/handbook/basic-types.html#null-and-undefined
-[ts-number]: https://www.typescriptlang.org/docs/handbook/basic-types.html#number
-[ts-object]: https://www.typescriptlang.org/docs/handbook/basic-types.html#object
-[ts-string]: https://www.typescriptlang.org/docs/handbook/basic-types.html#string
-[ts-undefined]: https://www.typescriptlang.org/docs/handbook/basic-types.html#null-and-undefined
-[ts-unknown]: https://www.typescriptlang.org/docs/handbook/basic-types.html#unknown
diff --git a/_config.yml b/_config.yml
new file mode 100644
index 00000000..2f7efbea
--- /dev/null
+++ b/_config.yml
@@ -0,0 +1 @@
+theme: jekyll-theme-minimal
\ No newline at end of file
diff --git a/index.md b/index.md
new file mode 100644
index 00000000..97b9bb19
--- /dev/null
+++ b/index.md
@@ -0,0 +1,37 @@
+## Welcome to GitHub Pages
+
+You can use the [editor on GitHub](https://github.com/angular-package/type/edit/gh-pages/index.md) to maintain and preview the content for your website in Markdown files.
+
+Whenever you commit to this repository, GitHub Pages will run [Jekyll](https://jekyllrb.com/) to rebuild the pages in your site, from the content in your Markdown files.
+
+### Markdown
+
+Markdown is a lightweight and easy-to-use syntax for styling your writing. It includes conventions for
+
+```markdown
+Syntax highlighted code block
+
+# Header 1
+## Header 2
+### Header 3
+
+- Bulleted
+- List
+
+1. Numbered
+2. List
+
+**Bold** and _Italic_ and `Code` text
+
+[Link](url) and ![Image](src)
+```
+
+For more details see [GitHub Flavored Markdown](https://guides.github.com/features/mastering-markdown/).
+
+### Jekyll Themes
+
+Your Pages site will use the layout and styles from the Jekyll theme you have selected in your [repository settings](https://github.com/angular-package/type/settings/pages). The name of this theme is saved in the Jekyll `_config.yml` configuration file.
+
+### Support or Contact
+
+Having trouble with Pages? Check out our [documentation](https://docs.github.com/categories/github-pages-basics/) or [contact support](https://support.github.com/contact) and we’ll help you sort it out.
diff --git a/karma.conf.js b/karma.conf.js
deleted file mode 100644
index a84e2991..00000000
--- a/karma.conf.js
+++ /dev/null
@@ -1,44 +0,0 @@
-// Karma configuration file, see link for more information
-// https://karma-runner.github.io/1.0/config/configuration-file.html
-
-module.exports = function (config) {
-  config.set({
-    basePath: '',
-    frameworks: ['jasmine', '@angular-devkit/build-angular'],
-    plugins: [
-      require('karma-jasmine'),
-      require('karma-chrome-launcher'),
-      require('karma-jasmine-html-reporter'),
-      require('karma-coverage'),
-      require('@angular-devkit/build-angular/plugins/karma')
-    ],
-    client: {
-      jasmine: {
-        // you can add configuration options for Jasmine here
-        // the possible options are listed at https://jasmine.github.io/api/edge/Configuration.html
-        // for example, you can disable the random execution with `random: false`
-        // or set a specific seed with `seed: 4321`
-      },
-      clearContext: false // leave Jasmine Spec Runner output visible in browser
-    },
-    jasmineHtmlReporter: {
-      suppressAll: true // removes the duplicated traces
-    },
-    coverageReporter: {
-      dir: require('path').join(__dirname, '../../coverage/type'),
-      subdir: '.',
-      reporters: [
-        { type: 'html' },
-        { type: 'text-summary' }
-      ]
-    },
-    reporters: ['progress', 'kjhtml'],
-    port: 9876,
-    colors: true,
-    logLevel: config.LOG_INFO,
-    autoWatch: true,
-    browsers: ['Chrome'],
-    singleRun: false,
-    restartOnFileChange: true
-  });
-};
diff --git a/ng-package.json b/ng-package.json
deleted file mode 100644
index b6fe1d9c..00000000
--- a/ng-package.json
+++ /dev/null
@@ -1,7 +0,0 @@
-{
-  "$schema": "../../node_modules/ng-packagr/ng-package.schema.json",
-  "dest": "../../dist/type",
-  "lib": {
-    "entryFile": "src/public-api.ts"
-  }
-}
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
deleted file mode 100644
index 03c1f281..00000000
--- a/package-lock.json
+++ /dev/null
@@ -1,22 +0,0 @@
-{
-  "name": "@angular-package/type",
-  "version": "5.0.1-rc.0",
-  "lockfileVersion": 1,
-  "requires": true,
-  "dependencies": {
-    "@angular-package/testing": {
-      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/@angular-package/testing/-/testing-1.1.0.tgz",
-      "integrity": "sha512-N/c75WBG4GPcgj7NYWAKSE9IwcPSqVMOYjkZ3RU4rUZW5equkjZvQ4zWKc8S4lbxr1wPD6KxPy3T52xTsBW3Dw==",
-      "dev": true,
-      "requires": {
-        "tslib": "^2.2.0"
-      }
-    },
-    "tslib": {
-      "version": "2.3.1",
-      "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.3.1.tgz",
-      "integrity": "sha512-77EbyPPpMz+FRFRuAFlWMtmgUWGe9UOG2Z25NqCwiIjRhOf5iKGuzSe5P2w1laq+FkRy4p+PCuVkJSGkzTEKVw=="
-    }
-  }
-}
diff --git a/package.json b/package.json
deleted file mode 100644
index 430d52f7..00000000
--- a/package.json
+++ /dev/null
@@ -1,63 +0,0 @@
-{
-  "name": "@angular-package/type",
-  "version": "5.0.0-rc.0",
-  "description": "Common types, type guards and type checkers.",
-  "author": "Angular Package <angular-package@wvvw.dev> (https://wvvw.dev)",
-  "homepage": "https://github.com/angular-package/type#readme",
-  "dependencies": {
-    "tslib": "^2.3.0"
-  },
-  "publishConfig": {
-    "access": "public",
-    "registry": "https://registry.npmjs.org"
-  },
-  "devDependencies": {
-    "@angular-package/testing": "^2.0.0"
-  },
-  "keywords": [
-    "array",
-    "bigint",
-    "boolean",
-    "check",
-    "class",
-    "date",
-    "defined",
-    "determine",
-    "false",
-    "function",
-    "guard",
-    "instance",
-    "key",
-    "propertyKey",
-    "null",
-    "number",
-    "number between",
-    "number object",
-    "number type",
-    "object",
-    "primitive",
-    "RegExp",
-    "string",
-    "string length",
-    "string object",
-    "string type",
-    "symbol",
-    "undefined",
-    "true",
-    "type",
-    "types",
-    "type guards",
-    "typescript",
-    "angular-package",
-    "@angular-package",
-    "@angular-package/type"
-  ],
-  "repository": {
-    "type": "git",
-    "url": "git+https://github.com/angular-package/type.git"
-  },
-  "bugs": {
-    "url": "https://github.com/angular-package/type/issues"
-  },
-  "license": "MIT"
-}
diff --git a/src/are/index.ts b/src/are/index.ts
deleted file mode 100644
index dfd374d6..00000000
--- a/src/are/index.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-// Object.
-export { are } from './lib/are.object';
-// Function.
-export { areBigInt } from './lib/are-bigint.func';
-export { areBoolean } from './lib/are-boolean.func';
-export { areDate } from './lib/are-date.func';
-export { areDefined } from './lib/are-defined.func';
-export { areFalse } from './lib/are-false.func';
-export { areNull } from './lib/are-null.func';
-export { areNumber } from './lib/are-number.func';
-export { areRegExp } from './lib/are-regexp.func';
-export { areString } from './lib/are-string.func';
-export { areSymbol } from './lib/are-symbol.func';
-export { areTrue } from './lib/are-true.func';
-export { areUndefined } from './lib/are-undefined.func';
diff --git a/src/are/interface/are.interface.ts b/src/are/interface/are.interface.ts
deleted file mode 100644
index 39a0b3cc..00000000
--- a/src/are/interface/are.interface.ts
+++ /dev/null
@@ -1,82 +0,0 @@
-// Function.
-import { areBigInt } from '../lib/are-bigint.func';
-import { areBoolean } from '../lib/are-boolean.func';
-import { areDate } from '../lib/are-date.func';
-import { areDefined } from '../lib/are-defined.func';
-import { areFalse } from '../lib/are-false.func';
-import { areNull } from '../lib/are-null.func';
-import { areNumber } from '../lib/are-number.func';
-import { areRegExp } from '../lib/are-regexp.func';
-import { areString } from '../lib/are-string.func';
-import { areSymbol } from '../lib/are-symbol.func';
-import { areTrue } from '../lib/are-true.func';
-import { areUndefined } from '../lib/are-undefined.func';
-/**
- * Represents the shape of an object that contains  `are` prefixed functions.
- */
-export interface Are {
-  /**
-   * Checks if the values are a `bigint` type by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  bigint: typeof areBigInt;
-
-  /**
-   * Checks if the values are a `boolean` type or an instance of `Boolean` by using `every()`, `forEach()` and `some()` methods of the
-   * returned object.
-   */
-  boolean: typeof areBoolean;
-
-  /**
-   * Checks if the values are `Date` by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  date: typeof areDate;
-
-  /**
-   * Checks if the values are defined by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  defined: typeof areDefined;
-
-  /**
-   * Checks if the values are a `boolean` type or an instance of `Boolean` equal to `false` by using `every()`, `forEach()` and `some()`
-   * methods of the returned object.
-   */
-  false: typeof areFalse;
-
-  /**
-   * Checks if the values are `null` by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  null: typeof areNull;
-
-  /**
-   * Checks if the values are a `number` type or an instance of `Number` by using `every()`, `forEach()` and `some()` methods of the
-   * returned object.
-   */
-  number: typeof areNumber;
-
-  /**
-   * Checks if the values are regular expressions of `RegExp` by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  regexp: typeof areRegExp;
-
-  /**
-   * Checks if the values are a `string` type or an instance of `String` by using `every()`, `forEach()` and `some()` methods of the
-   * returned object.
-   */
-  string: typeof areString;
-
-  /**
-   * Checks if the values are a `symbol` type by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  symbol: typeof areSymbol;
-
-  /**
-   * Checks if the values are a `boolean` type or an instance of `Boolean` equal to `true` by using `every()`, `forEach()` and `some()`
-   * methods of the returned object.
-   */
-  true: typeof areTrue;
-
-  /**
-   * Checks if the values are `undefined` by using `every()`, `forEach()` and `some()` methods of the returned object.
-   */
-  undefined: typeof areUndefined;
-}
diff --git a/src/are/lib/are-bigint.func.ts b/src/are/lib/are-bigint.func.ts
deleted file mode 100644
index 823e35f6..00000000
--- a/src/are/lib/are-bigint.func.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isBigInt } from '../../is/lib/is-big-int.func';
-/**
- * Checks whether the values are a `bigint` type by using `every()`, `forEach()` and `some()` methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against a `bigint` type.
- * @returns The return value is an `object` of `every()`, `some()` and `forEach()` as methods of checking supplied `values`.
- * @angularpackage
- */
-export const areBigInt = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isBigInt, ...values);
diff --git a/src/are/lib/are-boolean.func.ts b/src/are/lib/are-boolean.func.ts
deleted file mode 100644
index 08e47902..00000000
--- a/src/are/lib/are-boolean.func.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isBoolean } from '../../is/lib/is-boolean.func';
-/**
- * Checks whether the values are a `boolean` type or an instance of `Boolean` by using `every()`, `forEach()` and `some()` methods of the
- * returned object.
- * @param values A rest parameter of `any` type to check its elements against a `boolean` type or an instance of `Boolean`.
- * @returns The return value is an `object` of `every()`, `some()` and `forEach()` as methods of checking supplied `values`.
- * @angularpackage
- */
-export const areBoolean = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isBoolean, ...values);
diff --git a/src/are/lib/are-date.func.ts b/src/are/lib/are-date.func.ts
deleted file mode 100644
index 4ec2c109..00000000
--- a/src/are/lib/are-date.func.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isDate } from '../../is/lib/is-date.func';
-/**
- * Checks whether the values are `Date` by using `every()`, `forEach()` and `some()` methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against `Date`.
- * @returns The return value is an `object` of `every()`, `some()` and `forEach()` as methods of checking supplied `values`.
- * @angularpackage
- */
-export const areDate = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isDate, ...values);
diff --git a/src/are/lib/are-defined.func.ts b/src/are/lib/are-defined.func.ts
deleted file mode 100644
index 53ed4704..00000000
--- a/src/are/lib/are-defined.func.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isDefined } from '../../is/lib/is-defined.func';
-/**
- * Checks whether the values are defined by using `every()`, `forEach()` and `some()` methods of the returned object.
- * @param values A rest parameter of `any` type to check whether its elements are defined.
- * @returns The return value is an `object` of `every()`, `some()` and `forEach()` as a methods of checking supplied `values`.
- * @angularpackage
- */
-export const areDefined = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isDefined, ...values);
diff --git a/src/are/lib/are-determiner.func.ts b/src/are/lib/are-determiner.func.ts
deleted file mode 100644
index d4c23091..00000000
--- a/src/are/lib/are-determiner.func.ts
+++ /dev/null
@@ -1,86 +0,0 @@
-// Function,
-import { isArray } from '../../is/lib/is-array.func';
-import { isFunction } from '../../is/lib/is-function.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ForEachCallback } from '../../type/foreach-callback.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * The function returns the object of `every()`, `forEach()` and `some()` methods to check given values with the test implemented
- * by the given `checkFn` function.
- * @var CommonPayload The `CommonPayload` generic type variable constrained by the object constrains the generic type variable
- * `Payload` of each returned method.
- * @param checkFn Function to test given `values`.
- * @param values A rest parameter of `any` type to check its elements against test given in the `checkFn` function.
- * @returns The return value is an `object` of `every()`, `some()` and `forEach()` as methods of checking supplied `values`.
- */
-export const areDeterminer = <CommonPayload extends object>(
-  checkFn: Function,
-  ...values: any[]
-) => {
-  return {
-    /**
-     * Checks whether every of the provided `values` pass the test implemented by the given `checkFn` function.
-     * @var Payload The `Payload` generic type variable constrained by the generic type variable `CommonPayload` indicates the type of
-     * optional parameter `payload` of the supplied `callback` function and `payload` optional parameter of the `areDeterminer().every()`
-     * method from which it captures its value.
-     * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of
-     * this check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle
-     * them before the `result` return. By default, it uses `resultCallback()` function.
-     * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback`
-     * function.
-     * @returns The return value is a `boolean` indicating whether the provided `values` passed the test implemented by the given `checkFn`
-     * function.
-     * @angularpackage
-     */
-    every: <Payload extends CommonPayload>(
-      callback: ResultCallback<any, Payload> = resultCallback,
-      payload?: Payload
-    ): boolean =>
-      callback(
-        values.every((value) => checkFn(value)),
-        values,
-        payload
-      ),
-
-    /**
-     * The `forEach()` method executes a provided callback function once for each element of the supplied `values`.
-     * @param forEachCallback A callback `function` of `ForEachCallback` type with parameters, the `value` that has been checked, the
-     * `result` of this check, `index` of each element, the provided `values` and `payload` of generic type variable `Payload` with
-     * optional properties from the provided `payload`, to handle.
-     * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback`
-     * function.
-     * @angularpackage
-     */
-    forEach: <Payload extends CommonPayload>(
-      forEachCallback: ForEachCallback<any, Payload>,
-      payload?: Payload
-    ) => {
-      isArray(values) &&
-        isFunction(forEachCallback) &&
-        values.forEach((value, index) =>
-          forEachCallback(checkFn(value), value, index, values, payload)
-        );
-    },
-
-    /**
-     * Checks whether some of the provided `values` pass the test implemented by the given `checkFn`.
-     * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of
-     * this check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle
-     * them before the `result` return. By default, it uses `resultCallback()` function.
-     * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback`
-     * function.
-     * @returns The return value is a `boolean` indicating whether some of the provided `values` passed the test of the given `checkFn`.
-     * @angularpackage
-     */
-    some: <Payload extends CommonPayload>(
-      callback: ResultCallback<any, Payload> = resultCallback,
-      payload?: Payload
-    ): boolean =>
-      callback(
-        isArray(values) ? values.some((value) => checkFn(value)) : false,
-        values,
-        payload
-      ),
-  };
-};
diff --git a/src/are/lib/are-false.func.ts b/src/are/lib/are-false.func.ts
deleted file mode 100644
index e15a1c8b..00000000
--- a/src/are/lib/are-false.func.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isFalse } from '../../is/lib/is-false.func';
-/**
- * Checks whether the values are a `boolean` type or an instance of `Boolean` equal to `false` by using `every()`, `forEach()` and `some()`
- * methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against a `boolean` type or an instance of `Boolean` equal to `false`.
- * @returns The return value is an `object` of `every()`, `some()` and `forEach()` as a methods of checking supplied `values`.
- * @angularpackage
- */
-export const areFalse = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isFalse, ...values);
diff --git a/src/are/lib/are-null.func.ts b/src/are/lib/are-null.func.ts
deleted file mode 100644
index 833a214c..00000000
--- a/src/are/lib/are-null.func.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isNull } from '../../is/lib/is-null.func';
-/**
- * Checks whether the values are `null` by using `every()`, `forEach()` and `some()` methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against `null`.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied `values`.
- * @angularpackage
- */
-export const areNull = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isNull, ...values);
diff --git a/src/are/lib/are-number.func.ts b/src/are/lib/are-number.func.ts
deleted file mode 100644
index 682c73e0..00000000
--- a/src/are/lib/are-number.func.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isNumber } from '../../is/lib/is-number.func';
-/**
- * Checks whether the values are a `number` type or an instance of `Number` by using `every()`, `forEach()` and `some()` methods of the
- * returned object.
- * @param values A rest parameter of `any` type to check its elements against a `number` type or an instance of `Number`.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied values.
- * @angularpackage
- */
-export const areNumber = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isNumber, ...values);
diff --git a/src/are/lib/are-regexp.func.ts b/src/are/lib/are-regexp.func.ts
deleted file mode 100644
index c6b4d3be..00000000
--- a/src/are/lib/are-regexp.func.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isRegExp } from '../../is/lib/is-regexp.func';
-/**
- * Checks whether the values are regular expressions of `RegExp` by using `every()`, `forEach()` and `some()` methods of the returned
- * object.
- * @param values A rest parameter of `any` type to check its elements against the regular expression of `RegExp`.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied `values`.
- * @angularpackage
- */
-export const areRegExp = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isRegExp, ...values);
diff --git a/src/are/lib/are-string.func.ts b/src/are/lib/are-string.func.ts
deleted file mode 100644
index e5a22a2f..00000000
--- a/src/are/lib/are-string.func.ts
+++ /dev/null
@@ -1,73 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isString } from '../../is/lib/is-string.func';
-/**
- * Checks if the values are a `string` type or an instance of `String` by using `every()`, `forEach()` and `some()` methods of the
- * returned object.
- * @param values A rest parameter of `any` type to check its elements against a `string` type or an instance of `String`.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied values.
- * @angularpackage
- */
-export const areString = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isString, ...values);
-
-// {
-//   return {
-//     /**
-//      * Checks if every of the provided `values` of `areString()` is a `string` type or an instance of `String`.
-//      * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of
-//      * this check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle
-//      * them before the `result` return. By default, it uses `resultCallback()` function.
-//      * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
-//      * @returns The return value is a `boolean` indicating whether the provided values of `areString()` are a `string` type or an instance
-//      * of `String`.
-//      */
-//     every: <Payload extends CommonPayload>(
-//       callback: ResultCallback<any, Payload> = resultCallback,
-//       payload?: Payload
-//     ): boolean =>
-//       callback(
-//         values.every((value) => isString(value)),
-//         values,
-//         payload
-//       ),
-
-//     /**
-//      * The `forEach()` method executes a provided callback function once for each element of the supplied `values` of `areString()`.
-//      * @param forEachCallback A callback `function` of `ForEachCallback` type with parameters, the `value` that has been checked, the
-//      * `result` of this check, `index` of each element, the provided `values` and `payload` of generic type variable `Payload` with
-//      * optional properties from the provided `payload`, to handle them before the `result` return.
-//      * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
-//      * @returns The return value is void.
-//      */
-//     forEach: <Payload extends CommonPayload>(
-//       forEachCallback: ForEachCallback<any, Payload>,
-//       payload?: Payload
-//     ) => {
-//       if (isArray(values) && isFunction(forEachCallback)) {
-//         values.forEach((value, index) =>
-//           forEachCallback(isString(value), value, index, values, payload)
-//         );
-//       }
-//     },
-
-//     /**
-//      * Checks if some of the provided `values` of `areString()` are a `string` type or an instance of `String`.
-//      * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of
-//      * this check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle
-//      * them before the `result` return. By default, it uses `resultCallback()` function.
-//      * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
-//      * @returns The return value is a `boolean` indicating whether some of the provided values of `areString()` are a `string` type or an
-//      * instance of `String`.
-//      */
-//     some: <Payload extends CommonPayload>(
-//       callback: ResultCallback<any, Payload> = resultCallback,
-//       payload?: Payload
-//     ): boolean =>
-//       callback(
-//         isArray(values) ? values.some((value) => isString(value)) : false,
-//         values,
-//         payload
-//       ),
-//   };
-// };
diff --git a/src/are/lib/are-symbol.func.ts b/src/are/lib/are-symbol.func.ts
deleted file mode 100644
index d027879c..00000000
--- a/src/are/lib/are-symbol.func.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isSymbol } from '../../is/lib/is-symbol.func';
-/**
- * Checks whether the values are a `symbol` type by using `every()`, `forEach()` and `some()` methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against a `symbol` type.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied values.
- * @angularpackage
- */
-export const areSymbol = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isSymbol, ...values);
diff --git a/src/are/lib/are-true.func.ts b/src/are/lib/are-true.func.ts
deleted file mode 100644
index 784c1a20..00000000
--- a/src/are/lib/are-true.func.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isTrue } from '../../is/lib/is-true.func';
-/**
- * Checks whether the values are a `boolean` type or an instance of `Boolean` equal to `true` by using `every()`, `forEach()` and `some()`
- * methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against a `boolean` type or an instance of `Boolean` equal to `true`.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied `values`.
- * @angularpackage
- */
-export const areTrue = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isTrue, ...values);
diff --git a/src/are/lib/are-undefined.func.ts b/src/are/lib/are-undefined.func.ts
deleted file mode 100644
index a5bdc90b..00000000
--- a/src/are/lib/are-undefined.func.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-// Function.
-import { areDeterminer } from './are-determiner.func';
-import { isUndefined } from '../../is/lib/is-undefined.func';
-/**
- * Checks whether the values are `undefined` by using `every()`, `forEach()` and `some()` methods of the returned object.
- * @param values A rest parameter of `any` type to check its elements against `undefined`.
- * @returns The return value is an `object` with `every()`, `some()` and `forEach()` as a methods of checking supplied values.
- * @angularpackage
- */
-export const areUndefined = <CommonPayload extends object>(...values: any[]) =>
-  areDeterminer<CommonPayload>(isUndefined, ...values);
diff --git a/src/are/lib/are.object.ts b/src/are/lib/are.object.ts
deleted file mode 100644
index 240e7eb0..00000000
--- a/src/are/lib/are.object.ts
+++ /dev/null
@@ -1,32 +0,0 @@
-// Function.
-import { areBigInt } from '../lib/are-bigint.func';
-import { areBoolean } from '../lib/are-boolean.func';
-import { areDate } from './are-date.func';
-import { areDefined } from './are-defined.func';
-import { areFalse } from './are-false.func';
-import { areNull } from '../lib/are-null.func';
-import { areNumber } from '../lib/are-number.func';
-import { areRegExp } from './are-regexp.func';
-import { areString } from '../lib/are-string.func';
-import { areSymbol } from '../lib/are-symbol.func';
-import { areTrue } from './are-true.func';
-import { areUndefined } from '../lib/are-undefined.func';
-// Interface.
-import { Are } from '../interface/are.interface';
-/**
- * The `object` consists of `are` prefixed functions.
- */
-export const are: Are = Object.freeze({
-  bigint: areBigInt, // From the `5.0.0` version.
-  boolean: areBoolean, // From the `5.0.0` version.
-  date: areDate, // From the `5.0.0` version.
-  defined: areDefined, // From the `5.0.0` version.
-  false: areFalse, // From the `5.0.0` version.
-  null: areNull, // From the `5.0.0` version.
-  number: areNumber, // From the `5.0.0` version.
-  regexp: areRegExp, // From the `5.0.0` version.
-  string: areString,
-  symbol: areSymbol, // From the `5.0.0` version.
-  true: areTrue, // From the `5.0.0` version.
-  undefined: areUndefined // From the `5.0.0` version.
-});
diff --git a/src/are/test/are-bigint.spec.ts b/src/are/test/are-bigint.spec.ts
deleted file mode 100644
index 60966b17..00000000
--- a/src/are/test/are-bigint.spec.ts
+++ /dev/null
@@ -1,63 +0,0 @@
-
-import { areBigInt } from '../lib/are-bigint.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.bigint.describe,
-  tests.are.bigint.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areBigInt.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areBigInt).toBeDefined())
-    .it(`every()`, () => {
-      areBigInt(1n, '2n', 3, 4n).every(
-        (result, value, payload) => {
-          expect(value).toEqual([1n, '2n', 3, 4n]);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areBigInt(1n, '2n', 3, 4n).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areBigInt(1n, '2n', 3, 4n).some(
-        (result, value, payload) => {
-          expect(value).toEqual([1n, '2n', 3, 4n]);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-boolean.spec.ts b/src/are/test/are-boolean.spec.ts
deleted file mode 100644
index ebe73973..00000000
--- a/src/are/test/are-boolean.spec.ts
+++ /dev/null
@@ -1,64 +0,0 @@
-import { areBoolean } from '../lib/are-boolean.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.boolean.describe,
-  tests.are.boolean.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areBoolean.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areBoolean).toBeDefined())
-    .it(`every()`, () => {
-      areBoolean(1, true, null, new Boolean(3)).every(
-        (result, value, payload) => {
-          expect(result).toBeFalse();
-          expect(value).toEqual([1, true, null, new Boolean(3)]);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areBoolean(1, true, null, new Boolean(3)).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areBoolean(1, true, null, new Boolean(3)).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual([1, true, null, new Boolean(3)]);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-date.spec.ts b/src/are/test/are-date.spec.ts
deleted file mode 100644
index 73e58228..00000000
--- a/src/are/test/are-date.spec.ts
+++ /dev/null
@@ -1,66 +0,0 @@
-import { areDate } from '../lib/are-date.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.date.describe,
-  tests.are.date.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areDate.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areDate).toBeDefined())
-    .it(`every()`, () => {
-      const arr = [new Date(), new Date('invalid date')];
-      areDate(...arr).every(
-        (result, value, payload) => {
-          expect(result).toBeFalse();
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areDate(new Date(), new Date('invalid date')).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      const arr = [new Date(), new Date('invalid date')];
-      areDate(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-defined.spec.ts b/src/are/test/are-defined.spec.ts
deleted file mode 100644
index cff156df..00000000
--- a/src/are/test/are-defined.spec.ts
+++ /dev/null
@@ -1,65 +0,0 @@
-import { areDefined } from '../lib/are-defined.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.defined.describe,
-  tests.are.defined.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areDefined.name, () => {
-  let age: any;
-  const arr = ['1', 2, null, undefined, age];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areDefined).toBeDefined())
-    .it(`every()`, () => {
-      areDefined(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areDefined('1', 2, null, undefined, age).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areDefined(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-false.spec.ts b/src/are/test/are-false.spec.ts
deleted file mode 100644
index bca9d7b2..00000000
--- a/src/are/test/are-false.spec.ts
+++ /dev/null
@@ -1,65 +0,0 @@
-import { areFalse } from '../lib/are-false.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.false.describe,
-  tests.are.false.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areFalse.name, () => {
-  const arr = [true, null, false, new Boolean(false)];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areFalse).toBeDefined())
-    .it(`every()`, () => {
-      areFalse(...arr).every(
-        (result, value, payload) => {
-          expect(result).toBeFalse();
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areFalse(true, null, false, new Boolean(false)).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areFalse(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-null.spec.ts b/src/are/test/are-null.spec.ts
deleted file mode 100644
index 5aa069f4..00000000
--- a/src/are/test/are-null.spec.ts
+++ /dev/null
@@ -1,63 +0,0 @@
-import { areNull } from '../lib/are-null.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.null.describe,
-  tests.are.null.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areNull.name, () => {
-  const arr = [null, undefined, false, !!null];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areNull).toBeDefined())
-    .it(`every()`, () => {
-      areNull(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areNull(null, undefined, false, !!null).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areNull(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-number.spec.ts b/src/are/test/are-number.spec.ts
deleted file mode 100644
index 544b9c02..00000000
--- a/src/are/test/are-number.spec.ts
+++ /dev/null
@@ -1,64 +0,0 @@
-import { areNumber } from '../lib/are-number.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.number.describe,
-  tests.are.number.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areNumber.name, () => {
-  const arr = [1, new Number(2), Number(3), '4'];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areNumber).toBeDefined())
-    .it(`every()`, () => {
-      areNumber(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areNumber(1, new Number(2), Number(3), '4').forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areNumber(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-regexp.spec.ts b/src/are/test/are-regexp.spec.ts
deleted file mode 100644
index 7d215d20..00000000
--- a/src/are/test/are-regexp.spec.ts
+++ /dev/null
@@ -1,64 +0,0 @@
-import { areRegExp } from '../lib/are-regexp.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.regexp.describe,
-  tests.are.regexp.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areRegExp.name, () => {
-  const arr = [/^[]/, /^[]/, /^[]/, 3];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areRegExp).toBeDefined())
-    .it(`every()`, () => {
-      areRegExp(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areRegExp(...arr).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areRegExp(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-string.spec.ts b/src/are/test/are-string.spec.ts
deleted file mode 100644
index 3cb27b11..00000000
--- a/src/are/test/are-string.spec.ts
+++ /dev/null
@@ -1,65 +0,0 @@
-
-import { areString } from '../lib/are-string.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.string.describe,
-  tests.are.string.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areString.name, () => {
-  const arr = [1, '2', '3'];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areString).toBeDefined())
-    .it(`every()`, () => {
-      areString(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areString(...arr).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areString(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-symbol.spec.ts b/src/are/test/are-symbol.spec.ts
deleted file mode 100644
index ecc8c38a..00000000
--- a/src/are/test/are-symbol.spec.ts
+++ /dev/null
@@ -1,65 +0,0 @@
-// Function to test.
-import { areSymbol } from '../lib/are-symbol.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.symbol.describe,
-  tests.are.symbol.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areSymbol.name, () => {
-  const arr = [Symbol(1), 2, Symbol(3), 4];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areSymbol).toBeDefined())
-    .it(`every()`, () => {
-      areSymbol(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areSymbol(...arr).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areSymbol(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-true.spec.ts b/src/are/test/are-true.spec.ts
deleted file mode 100644
index 4240f513..00000000
--- a/src/are/test/are-true.spec.ts
+++ /dev/null
@@ -1,65 +0,0 @@
-// Function to test.
-import { areTrue } from '../lib/are-true.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.true.describe,
-  tests.are.true.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areTrue.name, () => {
-  const arr = [true, null, false, new Boolean(false)];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areTrue).toBeDefined())
-    .it(`every()`, () => {
-      areTrue(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areTrue(...arr).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areTrue(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/are/test/are-undefined.spec.ts b/src/are/test/are-undefined.spec.ts
deleted file mode 100644
index 5e898f15..00000000
--- a/src/are/test/are-undefined.spec.ts
+++ /dev/null
@@ -1,66 +0,0 @@
-
-// Function to test.
-import { areUndefined } from '../lib/are-undefined.func';
-// Testing.
-import {
-  Testing,
-  TestingToBeMatchers,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.are.undefined.describe,
-  tests.are.undefined.it
-);
-const toBe = new TestingToBeMatchers();
-/**
- * Tests.
- */
-testing.describe(areUndefined.name, () => {
-  const arr = [undefined, 1, 2, '3'];
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(areUndefined).toBeDefined())
-    .it(`every()`, () => {
-      areUndefined(...arr).every(
-        (result, value, payload) => {
-          expect(value).toEqual(arr);
-          toBe
-            .false(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    })
-    .it(`forEach()`, () => {
-      areUndefined(...arr).forEach(
-        (result, value, index, array, payload) => {
-          expect(value).toEqual(array[index]);
-          toBe
-            .boolean(result)
-            .number(index)
-            .array(array)
-            .object(payload);
-          expect(payload?.age).toEqual(2);
-        },
-        { age: 2 }
-      );
-    })
-    .it(`some()`, () => {
-      areUndefined(...arr).some(
-        (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(arr);
-          toBe
-            .true(result)
-            .array(value)
-            .undefined(payload);
-          return result;
-        }
-      );
-    });
-});
diff --git a/src/execute-tests.ts b/src/execute-tests.ts
deleted file mode 100644
index 589af52f..00000000
--- a/src/execute-tests.ts
+++ /dev/null
@@ -1,130 +0,0 @@
-export const tests = {
-  /**
-   * Switches for the `are` prefixed functions.
-   */
-  are: {
-    bigint: { describe: true, it: true },
-    boolean: { describe: true, it: true },
-    date: { describe: true, it: true },
-    defined: { describe: true, it: true },
-    false: { describe: true, it: true },
-    null: { describe: true, it: true },
-    number: { describe: true, it: true },
-    regexp: { describe: true, it: true },
-    string: { describe: true, it: true },
-    symbol: { describe: true, it: true },
-    true: { describe: true, it: true },
-    undefined: { describe: true, it: true },
-  },
-  object: {
-    guard: { describe: true, it: true },
-    is: { describe: true, it: true },
-    isNot: { describe: true, it: true },
-  },
-
-  /**
-   * Switches for the experimental.
-   */
-  experimental: {
-    bigint: { describe: true, it: true },
-    boolean: { describe: true, it: true },
-    number: { describe: true, it: true },
-    string: { describe: true, it: true },
-    symbol: { describe: true, it: true },
-  },
-
-  /**
-   * Switches for the `guard` prefixed functions.
-   */
-  guard: {
-    array: { describe: true, it: true },
-    bigint: { describe: true, it: true },
-    boolean: { describe: true, it: true },
-    class: { describe: true, it: true },
-    date: { describe: true, it: true },
-    defined: { describe: true, it: true },
-    false: { describe: true, it: true },
-    function: { describe: true, it: true },
-    instance: { describe: true, it: true },
-    key: { describe: true, it: true },
-    null: { describe: true, it: true },
-    number: { describe: true, it: true },
-    numberBetween: { describe: true, it: true },
-    object: { describe: true, it: true },
-    objectKey: { describe: true, it: true },
-    objectKeyIn: { describe: true, it: true },
-    objectKeys: { describe: true, it: true },
-    objectKeysIn: { describe: true, it: true },
-    objectSomeKeys: { describe: true, it: true },
-    primitive: { describe: true, it: true },
-    regexp: { describe: true, it: true },
-    string: { describe: true, it: true },
-    stringIncludes: { describe: true, it: true },
-    stringIncludesSome: { describe: true, it: true },
-    stringLength: { describe: true, it: true },
-    stringLengthBetween: { describe: true, it: true },
-    symbol: { describe: true, it: true },
-    true: { describe: true, it: true },
-    type: { describe: true, it: true },
-    undefined: { describe: true, it: true },
-  },
-
-  /**
-   * Switches for the `is` prefixed functions.
-   */
-  is: {
-    array: { describe: true, it: true },
-    bigint: { describe: true, it: true },
-    boolean: { describe: true, it: true },
-    booleanObject: { describe: true, it: true },
-    booleanType: { describe: true, it: true },
-    class: { describe: true, it: true },
-    date: { describe: true, it: true },
-    defined: { describe: true, it: true },
-    false: { describe: true, it: true },
-    function: { describe: true, it: true },
-    instance: { describe: true, it: true },
-    key: { describe: true, it: true },
-    not: {
-      boolean: { describe: true, it: true },
-      defined: { describe: true, it: true },
-      function: { describe: true, it: true },
-      null: { describe: true, it: true },
-      number: { describe: true, it: true },
-      string: { describe: true, it: true },
-      undefined: { describe: true, it: true },
-    },
-    null: { describe: true, it: true },
-    number: { describe: true, it: true },
-    numberBetween: { describe: true, it: true },
-    numberObject: { describe: true, it: true },
-    numberType: { describe: true, it: true },
-    object: { describe: true, it: true },
-    objectKey: { describe: true, it: true },
-    objectKeyIn: { describe: true, it: true },
-    objectKeys: { describe: true, it: true },
-    objectKeysIn: { describe: true, it: true },
-    objectSomeKeys: { describe: true, it: true },
-    param: { describe: true, it: true },
-    primitive: { describe: true, it: true },
-    regexp: { describe: true, it: true },
-    string: { describe: true, it: true },
-    stringIncludes: { describe: true, it: true },
-    stringIncludesSome: { describe: true, it: true },
-    stringLength: { describe: true, it: true },
-    stringLengthBetween: { describe: true, it: true },
-    stringObject: { describe: true, it: true },
-    stringType: { describe: true, it: true },
-    symbol: { describe: true, it: true },
-    true: { describe: true, it: true },
-    type: { describe: true, it: true },
-    undefined: { describe: true, it: true }
-  },
-
-  /**
-   * Switches for the recognize.
-   */
-  recognize: {
-    recognizeValue: { describe: true, it: true }
-  },
-};
diff --git a/src/guard/index.ts b/src/guard/index.ts
deleted file mode 100644
index 8ef86119..00000000
--- a/src/guard/index.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-// `guard` object.
-export { guard } from './lib/guard.object';
-// `guard` prefix functions,
-export { guardArray } from './lib/guard-array.func';
-export { guardBigInt } from './lib/guard-big-int.func';
-export { guardBoolean } from './lib/guard-boolean.func';
-export { guardClass } from './lib/guard-class.func';
-export { guardDate  } from './lib/guard-date.func';
-export { guardDefined } from './lib/guard-defined.func';
-export { guardFalse  } from './lib/guard-false.func';
-export { guardFunction } from './lib/guard-function.func';
-export { guardInstance } from './lib/guard-instance.func';
-export { guardKey } from './lib/guard-key.func';
-export { guardNull } from './lib/guard-null.func';
-export { guardNumber } from './lib/guard-number.func';
-export { guardNumberBetween } from './lib/guard-number-between.func';
-export { guardObject } from './lib/guard-object.func';
-export { guardObjectKey } from './lib/guard-object-key.func';
-export { guardObjectKeyIn } from './lib/guard-object-key-in.func';
-export { guardObjectKeysIn } from './lib/guard-object-keys-in.func';
-export { guardObjectKeys } from './lib/guard-object-keys.func';
-export { guardObjectSomeKeys } from './lib/guard-object-some-keys.func';
-export { guardPrimitive } from './lib/guard-primitive.func';
-export { guardRegExp } from './lib/guard-regexp.func';
-export { guardString } from './lib/guard-string.func';
-export { guardStringIncludes } from './lib/guard-string-includes.func';
-export { guardStringIncludesSome } from './lib/guard-string-includes-some.func';
-export { guardStringLength } from './lib/guard-string-length.func';
-export { guardStringLengthBetween } from './lib/guard-string-length-between.func';
-export { guardSymbol } from './lib/guard-symbol.func';
-export { guardTrue } from './lib/guard-true.func';
-export { guardType } from './lib/guard-type.func';
-export { guardUndefined } from './lib/guard-undefined.func';
diff --git a/src/guard/interface/guard-interface.ts b/src/guard/interface/guard-interface.ts
deleted file mode 100644
index ba811e36..00000000
--- a/src/guard/interface/guard-interface.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-// Interface.
-import { GuardIs } from './guard-is.interface';
-/**
- * The shape of an object with guard functions.
- */
-export interface Guard extends GuardIs { }
diff --git a/src/guard/interface/guard-is.interface.ts b/src/guard/interface/guard-is.interface.ts
deleted file mode 100644
index d5c25c43..00000000
--- a/src/guard/interface/guard-is.interface.ts
+++ /dev/null
@@ -1,154 +0,0 @@
-// Function.
-import { guardArray } from '../lib/guard-array.func';
-import { guardBigInt } from '../lib/guard-big-int.func';
-import { guardBoolean } from '../lib/guard-boolean.func';
-import { guardClass } from '../lib/guard-class.func';
-import { guardDate } from '../lib/guard-date.func';
-import { guardDefined } from '../lib/guard-defined.func';
-import { guardFalse } from '../lib/guard-false.func';
-import { guardFunction } from '../lib/guard-function.func';
-import { guardInstance } from '../lib/guard-instance.func';
-import { guardKey } from '../lib/guard-key.func';
-import { guardNull } from '../lib/guard-null.func';
-import { guardNumber } from '../lib/guard-number.func';
-import { guardNumberBetween } from '../lib/guard-number-between.func';
-import { guardObject } from '../lib/guard-object.func';
-import { guardObjectKey } from '../lib/guard-object-key.func';
-import { guardObjectKeyIn } from '../lib/guard-object-key-in.func';
-import { guardObjectKeys } from '../lib/guard-object-keys.func';
-import { guardObjectKeysIn } from '../lib/guard-object-keys-in.func';
-import { guardObjectSomeKeys } from '../lib/guard-object-some-keys.func';
-import { guardPrimitive } from '../lib/guard-primitive.func';
-import { guardRegExp } from '../lib/guard-regexp.func';
-import { guardString } from '../lib/guard-string.func';
-import { guardStringIncludes } from '../lib/guard-string-includes.func';
-import { guardStringIncludesSome } from '../lib/guard-string-includes-some.func';
-import { guardStringLength } from '../lib/guard-string-length.func';
-import { guardStringLengthBetween } from '../lib/guard-string-length-between.func';
-import { guardSymbol } from '../lib/guard-symbol.func';
-import { guardTrue } from '../lib/guard-true.func';
-import { guardType } from '../lib/guard-type.func';
-import { guardUndefined } from '../lib/guard-undefined.func';
-// Export: Interface.
-export interface GuardIs {
-  /**
-   * Guards the value to be an `array` of a generic type variable `Type`.
-   */
-  array: typeof guardArray;
-  /**
-   * Guards the value to be a `bigint`.
-   */
-  bigint: typeof guardBigInt;
-  /**
-   * Guards the value to be `boolean` of any type.
-   */
-  boolean: typeof guardBoolean;
-  /**
-   * Guards the value to be a `class` of generic type variable `Class`.
-   */
-  class: typeof guardClass;
-  /**
-   * Guards the value to be a date.
-   */
-  date: typeof guardDate;
-  /**
-   * Guards the value to be defined, not `undefined`.
-   */
-  defined: typeof guardDefined;
-  /**
-   * Guards the provided value to be `false`.
-   */
-  false: typeof guardFalse;
-  /**
-   * Guards the value to be a `Function`.
-   */
-  function: typeof guardFunction;
-  /**
-   * Guards the value to be an instance of the given `constructor`.
-   */
-  instance: typeof guardInstance;
-  /**
-   * Guards the value to be one of `string`, `number`, or `symbol` type.
-   */
-  key: typeof guardKey;
-  /**
-   * Guards the value to be `null`.
-   */
-  null: typeof guardNull;
-  /**
-   * Guards the value to be a `number` of any type.
-   */
-  number: typeof guardNumber;
-  /**
-   * Guards the value to be `number` between the specified range.
-   */
-  numberBetween: typeof guardNumberBetween;
-  /**
-   * Guards the value to be an `object` of a generic type variable `Obj`.
-   */
-  object: typeof guardObject;
-  /**
-   * Guards the value to be an `object` of generic type variable `Obj` that contains the given `key`.
-   */
-  objectKey: typeof guardObjectKey;
-  /**
-   * Guards the value to be an `object` of a generic type variable `Obj` that contains(or its prototype chain) the given `key`.
-   */
-  objectKeyIn: typeof guardObjectKeyIn;
-  /**
-   * Guards the value to be an `object` of a generic type variable `Obj` with its specified `keys`.
-   */
-  objectKeys: typeof guardObjectKeys;
-  /**
-   * Guards the value to be an `object` of a generic type variable `Obj` with specified keys in it(or its prototype chain).
-   */
-  objectKeysIn: typeof guardObjectKeysIn;
-  /**
-   * Guards the value to be an `object` of a generic type variable `Obj` with its specified `keys`.
-   */
-  objectSomeKeys: typeof guardObjectSomeKeys;
-  /**
-   * Guards the value to be the `Primitive` type or the given `type` of the `Primitives`.
-   */
-  primitive: typeof guardPrimitive;
-  /**
-   * Guards the value to be a `RegExp`.
-   */
-  regexp: typeof guardRegExp;
-  /**
-   * Guards the value to be `string` of any type.
-   */
-  string: typeof guardString;
-  /**
-   * Guards the value to be a `string` type or an instance of `String` that includes all of the specified words/sentences.
-   */
-  stringIncludes: typeof guardStringIncludes;
-  /**
-   * Guards the value to be a `string` type or an instance of `String` that includes some of the specified words/sentences.
-   */
-  stringIncludesSome: typeof guardStringIncludesSome;
-  /**
-   * Guards the value to be `string` type or `String` instance of a specified length.
-   */
-  stringLength: typeof guardStringLength;
-  /**
-   * Guards the value to be `string` or `String` instance of a length between the specified range.
-   */
-  stringLengthBetween: typeof guardStringLengthBetween;
-  /**
-   * Guards the value to be a `symbol`.
-   */
-  symbol: typeof guardSymbol;
-  /**
-   * Guards the value to be `true`.
-   */
-  true: typeof guardTrue;
-  /**
-   * Guards the value to be a type from a given `type`.
-   */
-  type: typeof guardType;
-  /**
-   * Guards the value to be `undefined`.
-   */
-  undefined: typeof guardUndefined;
-}
diff --git a/src/guard/lib/guard-array.func.ts b/src/guard/lib/guard-array.func.ts
deleted file mode 100644
index 3169574b..00000000
--- a/src/guard/lib/guard-array.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isArray } from '../../is/lib/is-array.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an `array` of a generic type variable `Type`.
- * @param value An `array` of generic type variable `Type` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return `value` is a `boolean` indicating whether the `value` is an `array` of a generic type variable `Type`.
- */
-export const guardArray = <Type, Payload extends object = object>(
-  value: Array<Type>,
-  callback?: ResultCallback<Array<Type>, Payload>,
-  payload?: Payload
-): value is Array<Type> => isArray(value, callback, payload);
diff --git a/src/guard/lib/guard-big-int.func.ts b/src/guard/lib/guard-big-int.func.ts
deleted file mode 100644
index d316d589..00000000
--- a/src/guard/lib/guard-big-int.func.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-// Function.
-import { isBigInt } from '../../is/lib/is-big-int.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `bigint`.
- * @param value A `bigint` type value to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return `value` is a `boolean` indicating whether the `value` is a `bigint`.
- */
-export const guardBigInt = <
-  BigInt extends bigint,
-  Payload extends object = object
->(
-  value: BigInt,
-  callback?: ResultCallback<BigInt, Payload>,
-  payload?: Payload
-): value is BigInt => isBigInt(value, callback, payload);
diff --git a/src/guard/lib/guard-boolean.func.ts b/src/guard/lib/guard-boolean.func.ts
deleted file mode 100644
index 4fd18fae..00000000
--- a/src/guard/lib/guard-boolean.func.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-// Function.
-import { isBoolean } from '../../is/lib/is-boolean.func';
-// Type.
-import { AnyBoolean } from '../../type/any-boolean.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be `boolean` of any type.
- * @param value The value of generic type variable `Type` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `boolean` type or an instance of `Boolean`.
- */
-export const guardBoolean = <
-  Type extends AnyBoolean,
-  Payload extends object = object
->(
-  value: Type,
-  callback?: ResultCallback<Type, Payload>,
-  payload?: Payload
-): value is Type => isBoolean(value, callback, payload);
diff --git a/src/guard/lib/guard-class.func.ts b/src/guard/lib/guard-class.func.ts
deleted file mode 100644
index b887be68..00000000
--- a/src/guard/lib/guard-class.func.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-// Function.
-import { isClass } from '../../is/lib/is-class.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `class` of generic type variable `Class`.
- * @param value The `class` of a generic type variable `Class` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `class` of a generic type variable `Class`.
- */
-export const guardClass = <
-  Class extends Function,
-  Payload extends object = object
->(
-  value: Class,
-  callback?: ResultCallback<Class, Payload>,
-  payload?: Payload
-): value is Class => isClass(value, callback, payload);
diff --git a/src/guard/lib/guard-date.func.ts b/src/guard/lib/guard-date.func.ts
deleted file mode 100644
index 1f713509..00000000
--- a/src/guard/lib/guard-date.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isDate } from '../../is/lib/is-date.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a date.
- * @param value The value of `Date` type to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the value is a date.
- */
-export const guardDate = <Payload extends object>(
-  value: Date,
-  callback?: ResultCallback<Date, Payload>,
-  payload?: Payload
-): value is Date => isDate(value, callback, payload);
diff --git a/src/guard/lib/guard-defined.func.ts b/src/guard/lib/guard-defined.func.ts
deleted file mode 100644
index 601a5adc..00000000
--- a/src/guard/lib/guard-defined.func.ts
+++ /dev/null
@@ -1,17 +0,0 @@
-// Function.
-import { isDefined } from '../../is/lib/is-defined.func';
-// Type.
-import { Defined } from '../../type/defined.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be defined, not `undefined`.
- * @param value The value of generic type `Defined<Type>`, never undefined type captured from itself to guard against `undefined`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is defined.
- */
-export const guardDefined = <Type, Payload extends object = object>(
-  value: Defined<Type>,
-  callback?: ResultCallback<Defined<Type>, Payload>,
-  payload?: Payload
-): value is Defined<Type> => isDefined(value, callback, payload);
diff --git a/src/guard/lib/guard-false.func.ts b/src/guard/lib/guard-false.func.ts
deleted file mode 100644
index 25a92f48..00000000
--- a/src/guard/lib/guard-false.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isFalse } from '../../is/lib/is-false.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the provided value to be `false`.
- * @param value The value of `false` type to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `boolean` type or an instance of `Boolean` equal to `false`.
- */
-export const guardFalse = <Payload extends object>(
-  value: false,
-  callback?: ResultCallback<false, Payload>,
-  payload?: Payload
-): value is false => isFalse(value, callback, payload);
diff --git a/src/guard/lib/guard-function.func.ts b/src/guard/lib/guard-function.func.ts
deleted file mode 100644
index 927dfd03..00000000
--- a/src/guard/lib/guard-function.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isFunction } from '../../is/lib/is-function.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `Function`.
- * @param value The `function` of a generic type variable `Type` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `Function`.
- */
-export const guardFunction = <Type extends Function, Payload extends object>(
-  value: Type,
-  callback?: ResultCallback<Type, Payload>,
-  payload?: Payload
-): value is Type => isFunction(value, callback, payload);
diff --git a/src/guard/lib/guard-instance.func.ts b/src/guard/lib/guard-instance.func.ts
deleted file mode 100644
index 02d0e0a3..00000000
--- a/src/guard/lib/guard-instance.func.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-// Function.
-import { isInstance } from '../../is/lib/is-instance.func';
-// Type.
-import { Constructor } from '../../type/constructor.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an instance of the given `constructor`.
- * @param value An `object` of a generic type variable `Obj` to guard and be compared with an instance of a given `constructor`.
- * @param constructor A `class` or `function` that specifies the type of the `constructor`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is an instance of a given `constructor`.
- */
-export const guardInstance = <
-  Obj extends object,
-  Payload extends object = object
->(
-  value: Obj,
-  constructor: Constructor<Obj>,
-  callback?: ResultCallback<Obj, { ctor: typeof constructor } & Payload>,
-  payload?: Payload
-): value is Obj => isInstance(value, constructor, callback, payload);
diff --git a/src/guard/lib/guard-is.object.ts b/src/guard/lib/guard-is.object.ts
deleted file mode 100644
index cdaf316d..00000000
--- a/src/guard/lib/guard-is.object.ts
+++ /dev/null
@@ -1,66 +0,0 @@
-// Function.
-import { guardArray } from './guard-array.func';
-import { guardBigInt } from './guard-big-int.func';
-import { guardBoolean } from './guard-boolean.func';
-import { guardClass } from './guard-class.func';
-import { guardDate } from './guard-date.func';
-import { guardDefined } from './guard-defined.func';
-import { guardFalse } from './guard-false.func';
-import { guardFunction } from './guard-function.func';
-import { guardInstance } from './guard-instance.func';
-import { guardKey } from './guard-key.func';
-import { guardNull } from './guard-null.func';
-import { guardNumber } from './guard-number.func';
-import { guardNumberBetween } from './guard-number-between.func';
-import { guardObject } from './guard-object.func';
-import { guardObjectKey } from './guard-object-key.func';
-import { guardObjectKeyIn } from './guard-object-key-in.func';
-import { guardObjectKeys } from './guard-object-keys.func';
-import { guardObjectKeysIn } from './guard-object-keys-in.func';
-import { guardObjectSomeKeys } from './guard-object-some-keys.func';
-import { guardPrimitive } from './guard-primitive.func';
-import { guardRegExp } from './guard-regexp.func';
-import { guardString } from './guard-string.func';
-import { guardStringIncludes } from './guard-string-includes.func';
-import { guardStringIncludesSome } from './guard-string-includes-some.func';
-import { guardStringLength } from './guard-string-length.func';
-import { guardStringLengthBetween } from './guard-string-length-between.func';
-import { guardSymbol } from './guard-symbol.func';
-import { guardTrue } from './guard-true.func';
-import { guardType } from './guard-type.func';
-import { guardUndefined } from './guard-undefined.func';
-// Interface.
-import { GuardIs } from '../interface/guard-is.interface';
-// `guardIs`.
-export const guardIs: GuardIs = Object.freeze({
-  array: guardArray,
-  bigint: guardBigInt,
-  boolean: guardBoolean,
-  class: guardClass,
-  date: guardDate,
-  defined: guardDefined,
-  false: guardFalse,
-  function: guardFunction,
-  instance: guardInstance,
-  key: guardKey,
-  null: guardNull,
-  number: guardNumber,
-  numberBetween: guardNumberBetween,
-  object: guardObject,
-  objectKey: guardObjectKey,
-  objectKeyIn: guardObjectKeyIn,
-  objectKeys: guardObjectKeys,
-  objectKeysIn: guardObjectKeysIn,
-  objectSomeKeys: guardObjectSomeKeys,
-  primitive: guardPrimitive,
-  regexp: guardRegExp,
-  string: guardString,
-  stringIncludes: guardStringIncludes,
-  stringIncludesSome: guardStringIncludesSome,
-  stringLength: guardStringLength,
-  stringLengthBetween: guardStringLengthBetween,
-  symbol: guardSymbol,
-  true: guardTrue,
-  type: guardType,
-  undefined: guardUndefined
-});
diff --git a/src/guard/lib/guard-key.func.ts b/src/guard/lib/guard-key.func.ts
deleted file mode 100644
index fed9ad5d..00000000
--- a/src/guard/lib/guard-key.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isKey } from '../../is/lib/is-key.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be one of `string`, `number`, or `symbol` type.
- * @param value The value of generic type variable `Key` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `string`, `number`, or `symbol`.
- */
-export const guardKey = <Key extends PropertyKey, Payload extends object>(
-  value: Key,
-  callback?: ResultCallback<Key, Payload>,
-  payload?: Payload
-): value is Key => isKey(value, callback, payload);
diff --git a/src/guard/lib/guard-null.func.ts b/src/guard/lib/guard-null.func.ts
deleted file mode 100644
index 9d84a471..00000000
--- a/src/guard/lib/guard-null.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isNull } from '../../is/lib/is-null.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be `null`.
- * @param value The value of `null` type to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is `null`.
- */
-export const guardNull = <Payload extends object>(
-  value: null,
-  callback?: ResultCallback<null, Payload>,
-  payload?: Payload
-): value is null => isNull(value, callback, payload);
diff --git a/src/guard/lib/guard-number-between.func.ts b/src/guard/lib/guard-number-between.func.ts
deleted file mode 100644
index 99709515..00000000
--- a/src/guard/lib/guard-number-between.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { isNumberBetween } from '../../is/lib/is-number-between.func';
-// Type.
-import { AnyNumber } from '../../type/any-number.type';
-import { NumberBetween } from '../../type/number-between.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be `number` type or instance of `Number` between the specified range.
- * @param value The value of a generic type variable `Type` to guard.
- * @param min The **minimum** range of generic type variable `Min` for a given `value`.
- * @param max The **maximum** range of generic type variable `Max` for a given `value`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `number` type or an instance of `Number` between the
- * specified range.
- */
-export const guardNumberBetween = <
-  Type extends AnyNumber,
-  Min extends number,
-  Max extends number,
-  Payload extends object = object
->(
-  value: Type,
-  min: Min,
-  max: Max,
-  callback?: ResultCallback<Type, { min: Min; max: Max } & Payload>,
-  payload?: Payload
-): value is NumberBetween<Min, Max, Type> =>
-  isNumberBetween(value, min, max, callback, payload);
diff --git a/src/guard/lib/guard-number.func.ts b/src/guard/lib/guard-number.func.ts
deleted file mode 100644
index 61093a7c..00000000
--- a/src/guard/lib/guard-number.func.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-// Function.
-import { isNumber } from '../../is/lib/is-number.func';
-// Type.
-import { AnyNumber } from '../../type/any-number.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `number` of any type.
- * @param value The value of generic type variable `Type` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `number` type or an instance of `Number`.
- */
-export const guardNumber = <
-  Type extends AnyNumber,
-  Payload extends object = object
->(
-  value: Type,
-  callback?: ResultCallback<Type, Payload>,
-  payload?: Payload
-): value is Type => isNumber(value, callback, payload);
diff --git a/src/guard/lib/guard-object-key-in.func.ts b/src/guard/lib/guard-object-key-in.func.ts
deleted file mode 100644
index 9022118b..00000000
--- a/src/guard/lib/guard-object-key-in.func.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-// Function.
-import { isObjectKeyIn } from '../../is/lib/is-object-key-in.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the `value` to be an `object` of a generic type variable `Obj` that contains(or its prototype chain) the given `key`.
- * @param value An `object` of a generic type variable `Obj`, by default of the type captured from itself that contains(or its prototype
- * chain) the given `key`.
- * @param key A key of generic type variable `Key` as the property name that the given `value` contains(or its prototype chain).
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is an `object` that contains(or its prototype chain) the given
- * `key`.
- */
-export const guardObjectKeyIn = <
-  Obj extends object,
-  Key extends keyof Obj,
-  Payload extends object = object
->(
-  value: Obj,
-  key: Key,
-  callback?: ResultCallback<Obj, { key: typeof key } & Payload>,
-  payload?: Payload
-): value is Obj => isObjectKeyIn(value, key, callback, payload as any);
diff --git a/src/guard/lib/guard-object-key.func.ts b/src/guard/lib/guard-object-key.func.ts
deleted file mode 100644
index 059f4a67..00000000
--- a/src/guard/lib/guard-object-key.func.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-// Function.
-import { isObjectKey } from '../../is/lib/is-object-key.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an `object` of generic type variable `Obj` that contains the given `key`.
- * @param value An `object` of a generic type variable `Obj`, by default of the type captured from itself that contains the given `key` to
- * guard.
- * @param key A key of generic type variable `Key` as the property name that the given `value` contains.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is an `object` of generic type variable `Obj` that contains the
- * given `key`.
- */
-export const guardObjectKey = <
-  Obj extends object,
-  Key extends keyof Obj,
-  Payload extends object = object
->(
-  value: Obj,
-  key: Key,
-  callback?: ResultCallback<Obj, { key: typeof key } & Payload>,
-  payload?: Payload
-): value is Obj => isObjectKey(value, key, callback, payload as any);
diff --git a/src/guard/lib/guard-object-keys-in.func.ts b/src/guard/lib/guard-object-keys-in.func.ts
deleted file mode 100644
index 0807af7e..00000000
--- a/src/guard/lib/guard-object-keys-in.func.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-// Function.
-import { isObjectKeysIn } from '../../is/lib/is-object-keys-in.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an `object` of a generic type variable `Obj` with specified keys in it(or its prototype chain).
- * @param value An object of a generic type variable `Obj`, by default of the type captured from itself that contains(or its prototype
- * chain) the given `keys` to guard.
- * @param keys An `Array` of property keys to check whether the given `value` contains(or its prototype chain).
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is an `object` with specified `keys` in it(or its prototype
- * chain).
- */
-export const guardObjectKeysIn = <
-  Obj extends object,
-  Key extends keyof Obj,
-  Payload extends object = object
->(
-  value: Obj,
-  keys: Key[],
-  callback?: ResultCallback<Obj, { keys: typeof keys } & Payload>,
-  payload?: Payload
-): value is Obj => isObjectKeysIn(value, keys, callback, payload as any);
diff --git a/src/guard/lib/guard-object-keys.func.ts b/src/guard/lib/guard-object-keys.func.ts
deleted file mode 100644
index f2793bd1..00000000
--- a/src/guard/lib/guard-object-keys.func.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-// Function.
-import { isObjectKeys } from '../../is/lib/is-object-keys.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an `object` of a generic type variable `Obj` with its specified `keys`.
- * @param value An object of a generic type variable `Obj`, by default of the type captured from itself that contains the given `keys` to
- * guard.
- * @param keys An `Array` of property keys to check whether the given `value` contains.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is an `object` with its specified `keys`.
- */
-export const guardObjectKeys = <
-  Obj extends object,
-  Key extends keyof Obj,
-  Payload extends object = object
->(
-  value: Obj,
-  keys: Key[],
-  callback?: ResultCallback<Obj, { keys: typeof keys } & Payload>,
-  payload?: Payload
-): value is Obj => isObjectKeys(value, keys, callback, payload as any);
diff --git a/src/guard/lib/guard-object-some-keys.func.ts b/src/guard/lib/guard-object-some-keys.func.ts
deleted file mode 100644
index 89d6c5e7..00000000
--- a/src/guard/lib/guard-object-some-keys.func.ts
+++ /dev/null
@@ -1,25 +0,0 @@
-// Function.
-import { isObjectSomeKeys } from '../../is/lib/is-object-some-keys.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an `object` of a generic type variable `Obj` with some of its `keys` or some groups of its `keys`.
- * @param value An object of a generic type variable `Obj`, by default of the type captured from itself that contains some or some of the
- * groups of the given `keys`, to guard.
- * @param keys An `Array` of property names or a two-dimensional array of property names to check if the given `value` contains some of
- * them.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` with some or some groups of the given
- * `keys`.
- * @angularpackage
- */
-export const guardObjectSomeKeys = <
-  Obj extends object,
-  Payload extends object = object
->(
-  value: Obj,
-  keys: (keyof Obj | Array<keyof Obj>)[],
-  callback?: ResultCallback<Obj, { keys: typeof keys } & Payload>,
-  payload?: Payload
-): value is Obj => isObjectSomeKeys(value, keys, callback, payload as any);
diff --git a/src/guard/lib/guard-object.func.ts b/src/guard/lib/guard-object.func.ts
deleted file mode 100644
index 5c0055fd..00000000
--- a/src/guard/lib/guard-object.func.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-// Function.
-import { isObject } from '../../is/lib/is-object.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be an `object` of a generic type variable `Obj`.
- * @param value An `object` of a generic type variable `Obj`, by default of the type captured from itself to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` of a generic type variable `Obj`.
- */
-export const guardObject = <
-  Obj extends object,
-  Payload extends object = object
->(
-  value: Obj,
-  callback?: ResultCallback<Obj, Payload>,
-  payload?: Payload
-): value is Obj => isObject(value, callback, payload);
diff --git a/src/guard/lib/guard-primitive.func.ts b/src/guard/lib/guard-primitive.func.ts
deleted file mode 100644
index 8ca5b48b..00000000
--- a/src/guard/lib/guard-primitive.func.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-// Function.
-import { isPrimitive } from '../../is/lib/is-primitive.func';
-// Type.
-import { Primitive } from '../../type/primitive.type';
-import { Primitives } from '../../type/primitives.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be the `Primitive` type or the given `type` of the `Primitives`.
- * @param value The value of a generic type variable `Type` constrained by the `Primitive`, by default of the type captured from itself to
- * guard.
- * @param type An optional specific type of `Primitives` to check the given value.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is the `Primitive` type or the given `type`.
- */
-export const guardPrimitive = <
-  Type extends Primitive,
-  Payload extends object = object
->(
-  value: Type,
-  type?: Primitives,
-  callback?: ResultCallback<Type, Payload>,
-  payload?: Payload
-): value is Type => isPrimitive(value, type, callback, payload);
diff --git a/src/guard/lib/guard-regexp.func.ts b/src/guard/lib/guard-regexp.func.ts
deleted file mode 100644
index f23b1f65..00000000
--- a/src/guard/lib/guard-regexp.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isRegExp } from '../../is/lib/is-regexp.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `RegExp`.
- * @param value Regular expression of generic type variable `Type` constrained by `RegExp` to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return `value` is a `boolean` indicating whether the `value` is a `RegExp`.
- */
-export const guardRegExp = <Type extends RegExp, Payload extends object>(
-  value: Type,
-  callback?: ResultCallback<Type, Payload>,
-  payload?: Payload
-): value is Type => isRegExp(value, callback, payload);
diff --git a/src/guard/lib/guard-string-includes-some.func.ts b/src/guard/lib/guard-string-includes-some.func.ts
deleted file mode 100644
index bfbd3be9..00000000
--- a/src/guard/lib/guard-string-includes-some.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { isStringIncludesSome } from '../../is/lib/is-string-includes-some.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `string` type or an instance of `String` that includes some of the specified words/sentences.
- * @param value The value of a generic type variable `Type` constrained by the `AnyString`, by default of the type captured from itself to
- * check against the `string` that contains some of the words/sentences from a given `includes`.
- * @param includes An `Array` of `string` as words/sentences to be case-sensitive searched for within the given `value`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String` that
- * includes all of the specified words/sentences.
- * @angularpackage
- */
-export const guardStringIncludesSome = <
-  Type extends AnyString,
-  Payload extends object = object
->(
-  value: Type,
-  includes: string[],
-  callback: ResultCallback<
-    Type,
-    { includes: typeof includes } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Type => isStringIncludesSome(value, includes, callback, payload);
diff --git a/src/guard/lib/guard-string-includes.func.ts b/src/guard/lib/guard-string-includes.func.ts
deleted file mode 100644
index b11bc594..00000000
--- a/src/guard/lib/guard-string-includes.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { isStringIncludes } from '../../is/lib/is-string-includes.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `string` type or an instance of `String` that includes the specified words/sentences.
- * @param value The value of a generic type variable `Type` constrained by the `AnyString`, by default of the type captured from itself to
- * check against the `string` that contains words/sentences from a given `includes`.
- * @param includes An `Array` of `string` as words/sentences to be case-sensitive searched for within the given `value`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String` that
- * includes the specified words/sentences.
- * @angularpackage
- */
-export const guardStringIncludes = <
-  Type extends AnyString,
-  Payload extends object = object
->(
-  value: Type,
-  includes: string[],
-  callback: ResultCallback<
-    Type,
-    { includes: typeof includes } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Type => isStringIncludes(value, includes, callback, payload);
diff --git a/src/guard/lib/guard-string-length-between.func.ts b/src/guard/lib/guard-string-length-between.func.ts
deleted file mode 100644
index a19f9b0a..00000000
--- a/src/guard/lib/guard-string-length-between.func.ts
+++ /dev/null
@@ -1,31 +0,0 @@
-// Function.
-import { isStringLengthBetween } from '../../is';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-import { StringOfLength } from '../../type/string-of-length.type';
-/**
- * Guards the value to be `string` or `String` instance of a length between the specified range.
- * @param value The value of a generic type variable `Type` constrained by `AnyString`, by default of the type captured from itself to
- * guard.
- * @param min The **minimum** length of generic type variable `Min` of a given `value`.
- * @param max The **maximum** length of generic type variable `Max` of a given `value`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `string` type or an instance of `String` of a length between
- * the specified range.
- * @angularpackage
- */
-export const guardStringLengthBetween = <
-  Type extends AnyString,
-  Min extends number,
-  Max extends number,
-  Payload extends object = object
->(
-  value: Type,
-  min: Min,
-  max: Max,
-  callback?: ResultCallback<Type, { min: Min; max: Max } & Payload>,
-  payload?: Payload
-): value is StringOfLength<Min, Max, Type> =>
-  isStringLengthBetween(value, min, max, callback, payload);
diff --git a/src/guard/lib/guard-string-length.func.ts b/src/guard/lib/guard-string-length.func.ts
deleted file mode 100644
index 5e17b14a..00000000
--- a/src/guard/lib/guard-string-length.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { isStringLength } from '../../is';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-import { StringOfLength } from '../../type/string-of-length.type';
-/**
- * Guards the value to be `string` type or `String` instance of a specified length.
- * @param value The value of a generic type variable `Type` constrained by `AnyString`, by default of the type captured from itself to
- * guard.
- * @param length The **length** of generic type variable `Length` of a given `value`.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `string` type or an instance of `String` of a specified
- * `length`.
- * @angularpackage
- */
-export const guardStringLength = <
-  Type extends AnyString,
-  Length extends number,
-  Payload extends object = object
->(
-  value: Type,
-  length: Length,
-  callback?: ResultCallback<Type, { length: Length } & Payload>,
-  payload?: Payload
-): value is StringOfLength<Length, Length, Type> =>
-  isStringLength(value, length, callback, payload);
-
diff --git a/src/guard/lib/guard-string.func.ts b/src/guard/lib/guard-string.func.ts
deleted file mode 100644
index 23114274..00000000
--- a/src/guard/lib/guard-string.func.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-// Function.
-import { isString } from '../../is/lib/is-string.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be `string` of any type.
- * @param value The value of a generic type variable `Type` constrained by the `AnyString`, by default of the type captured from itself to
- * guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `string` type or an instance of `String`.
- */
-export const guardString = <
-  Type extends AnyString,
-  Payload extends object = object
->(
-  value: Type,
-  callback?: ResultCallback<Type, Payload>,
-  payload?: Payload
-): value is Type => isString(value, callback, payload);
diff --git a/src/guard/lib/guard-symbol.func.ts b/src/guard/lib/guard-symbol.func.ts
deleted file mode 100644
index 89103a6b..00000000
--- a/src/guard/lib/guard-symbol.func.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-// Function.
-import { isSymbol } from '../../is/lib/is-symbol.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be a `symbol`.
- * @param value A `symbol` type value to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `symbol`.
- */
-export const guardSymbol = <Payload extends object>(
-  value: symbol,
-  callback?: ResultCallback<symbol, Payload>,
-  payload?: Payload
-): value is symbol => isSymbol(value, callback, payload);
diff --git a/src/guard/lib/guard-true.func.ts b/src/guard/lib/guard-true.func.ts
deleted file mode 100644
index 6d187e01..00000000
--- a/src/guard/lib/guard-true.func.ts
+++ /dev/null
@@ -1,17 +0,0 @@
-// Function.
-import { isTrue } from '../../is/lib/is-true.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be `true`.
- * @param value The value of `true` type to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a `boolean` type or an instance of `Boolean` equal to `true`.
- * @angularpackage
- */
-export const guardTrue = <Payload extends object>(
-  value: true,
-  callback?: ResultCallback<true, Payload>,
-  payload?: Payload
-): value is true => isTrue(value, callback, payload);
diff --git a/src/guard/lib/guard-type.func.ts b/src/guard/lib/guard-type.func.ts
deleted file mode 100644
index ff89794d..00000000
--- a/src/guard/lib/guard-type.func.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-// Function.
-import { isType } from '../../is/lib/is-type.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-import { Type } from '../../type/type.type';
-import { Types } from '../../type/types.type';
-/**
- * Guards the value to be a type of given `type`.
- * @param value The value of a generic type variable `T` constrained by the `Type`, by default of the type captured from itself, to guard.
- * @param type The value of `string` or `Constructor` type of the `Types` indicates against which type a given `value` is checked.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is a type from a given `type`.
- * @angularpackage
- */
-export const guardType = <T extends Type, Payload extends object = object>(
-  value: T,
-  type: Types<T>,
-  callback?: ResultCallback<T, Payload>,
-  payload?: Payload
-): value is T => isType(value, type, callback, payload);
diff --git a/src/guard/lib/guard-undefined.func.ts b/src/guard/lib/guard-undefined.func.ts
deleted file mode 100644
index 17f27da8..00000000
--- a/src/guard/lib/guard-undefined.func.ts
+++ /dev/null
@@ -1,17 +0,0 @@
-// Function.
-import { isUndefined } from '../../is/lib/is-undefined.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Guards the value to be `undefined`.
- * @param value The value of an `undefined` type to guard.
- * @param callback An optional `ResultCallback` function to handle the result before returns.
- * @param payload Optional `object` of generic type variable `Payload` is assigned to the `payload` of the provided `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is `undefined`.
- * @angularpackage
- */
-export const guardUndefined = <Payload extends object>(
-  value: undefined,
-  callback?: ResultCallback<undefined, Payload>,
-  payload?: Payload
-): value is undefined => isUndefined(value, callback, payload);
diff --git a/src/guard/lib/guard.object.ts b/src/guard/lib/guard.object.ts
deleted file mode 100644
index 54ee33cf..00000000
--- a/src/guard/lib/guard.object.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-// Import: Object.
-import { guardIs } from './guard-is.object';
-// Import: Interface.
-import { Guard } from '../interface/guard-interface';
-// Export: `guard`
-export const guard: Guard = Object.freeze({ ...guardIs });
diff --git a/src/guard/test/guard-array.spec.ts b/src/guard/test/guard-array.spec.ts
deleted file mode 100644
index c0626a6c..00000000
--- a/src/guard/test/guard-array.spec.ts
+++ /dev/null
@@ -1,53 +0,0 @@
-// Function.
-import { guardArray } from '../lib/guard-array.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_ARRAY_BIGINT,
-  TESTING_ARRAY_BOOLEAN,
-  TESTING_ARRAY_CLASS,
-  TESTING_ARRAY_FUNCTION,
-  TESTING_ARRAY_NULL,
-  TESTING_ARRAY_NUMBER,
-  TESTING_ARRAY_OBJECT_ONE,
-  TESTING_ARRAY_STRING,
-  TESTING_ARRAY_SYMBOL_NUMBER,
-  TESTING_ARRAY_SYMBOL_STRING,
-  TESTING_ARRAY_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.array.describe,
-  tests.guard.array.it
-);
-/**
- * Tests.
- */
-testing.describe(guardArray.name, () => {
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(guardArray).toBeDefined())
-    .it('Array<bigint>', () => expect(guardArray<bigint>(TESTING_ARRAY_BIGINT)).toBeTruthy())
-    .it('Array<boolean>', () => expect(guardArray<boolean | Boolean>(TESTING_ARRAY_BOOLEAN)).toBeTruthy())
-    .it('Array<TestingClass>', () => expect(guardArray<TestingClass>(TESTING_ARRAY_CLASS)).toBeTruthy())
-    .it('Array<Func>', () => expect(guardArray<Function>(TESTING_ARRAY_FUNCTION)).toBeTruthy())
-    .it('Array<null>', () => expect(guardArray<null>(TESTING_ARRAY_NULL)).toBeTruthy())
-    .it('Array<number>', () => expect(guardArray<number | Number>(TESTING_ARRAY_NUMBER)).toBeTruthy())
-    .it('Array<ObjectOne> Array<ObjectTwo>', () => expect(guardArray(TESTING_ARRAY_OBJECT_ONE)).toBeTruthy())
-    .it('Array<string>', () => expect(guardArray<string | String>(TESTING_ARRAY_STRING)).toBeTruthy())
-    .it('Array<symbol>', () => {
-      expect(guardArray(TESTING_ARRAY_SYMBOL_STRING)).toBeTruthy();
-      expect(guardArray(TESTING_ARRAY_SYMBOL_NUMBER)).toBeTruthy();
-    })
-    .it('Array<undefined>', () => expect(guardArray<undefined | unknown>(TESTING_ARRAY_UNDEFINED)).toBeTruthy());
-});
diff --git a/src/guard/test/guard-bigint.spec.ts b/src/guard/test/guard-bigint.spec.ts
deleted file mode 100644
index 09b16cc7..00000000
--- a/src/guard/test/guard-bigint.spec.ts
+++ /dev/null
@@ -1,52 +0,0 @@
-// Function.
-import { guardBigInt } from '../lib/guard-big-int.func';
-// Object.
-import { guard } from '../lib/guard.object';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.bigint.describe,
-  tests.guard.bigint.it
-);
-/**
- * Tests.
- */
-testing.describe(guardBigInt.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardBigInt).toBeDefined())
-    // Checks ...
-    .describe(`guards`, () => {
-      testing
-      .it('with callback and payload', () => {
-        guardBigInt(TESTING_BIGINT, (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(TESTING_BIGINT);
-          if (payload) {
-            expect(payload.action).toEqual('action');
-            expect(payload.name).toEqual('name');
-            expect(payload.param).toEqual('param');
-          }
-          return result;
-        }, { action: 'action', name: 'name', param: 'param' });
-      })
-      // ... primitives.
-      .describe(`primitive`, () =>
-        testing.describe(`bigint`, () =>
-          testing
-            .it(`${TESTING_BIGINT}`, () => expect(guardBigInt(TESTING_BIGINT)).toBeTrue())
-            .it(`${TESTING_BIGINT}`, () => expect(guard.bigint(TESTING_BIGINT)).toBeTrue())
-          ));
-    });
-});
diff --git a/src/guard/test/guard-boolean.spec.ts b/src/guard/test/guard-boolean.spec.ts
deleted file mode 100644
index 26bf101d..00000000
--- a/src/guard/test/guard-boolean.spec.ts
+++ /dev/null
@@ -1,70 +0,0 @@
-// Function.
-import { guardBoolean } from '../lib/guard-boolean.func';
-// Object.
-import { guard } from '../lib/guard.object';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.boolean.describe,
-  tests.guard.boolean.it
-);
-/**
- * Tests.
- */
-testing.describe(guardBoolean.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardBoolean).toBeDefined())
-    // Checks ...
-    .describe(`guards`, () => {
-      testing
-      .it('with callback and payload', () => {
-        guardBoolean(TESTING_TRUE, (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(TESTING_TRUE);
-          if (payload) {
-            expect(payload.action).toEqual('action');
-            expect(payload.name).toEqual('name');
-            expect(payload.param).toEqual('param');
-          }
-          return result;
-        }, { action: 'action', name: 'name', param: 'param' });
-      })
-      // ... primitives.
-      .describe(`primitive`, () => {
-        // boolean
-        testing.describe(`boolean`, () => {
-          testing
-            .it(`FALSE`, () => expect(guardBoolean(TESTING_FALSE)).toBeTrue())
-            .it(`TRUE`, () => expect(guardBoolean(TESTING_TRUE)).toBeTrue())
-            .it(`FALSE`, () => expect(guard.boolean(TESTING_FALSE)).toBeTrue())
-            .it(`TRUE`, () => expect(guard.boolean(TESTING_TRUE)).toBeTrue());
-        });
-      })
-      // ... instance.
-      .describe(`instance`, () => {
-        // boolean
-        testing.describe(`boolean`, () => {
-          testing
-            .it(`${TESTING_TRUE_INSTANCE}`, () => expect(guardBoolean(TESTING_TRUE_INSTANCE)).toBeTrue())
-            .it(`${TESTING_FALSE_INSTANCE}`, () => expect(guardBoolean(TESTING_FALSE_INSTANCE)).toBeTrue())
-            .it(`${TESTING_FALSE_INSTANCE}`, () => expect(guard.boolean(TESTING_FALSE_INSTANCE)).toBeTrue())
-            .it(`${TESTING_TRUE_INSTANCE}`, () => expect(guard.boolean(TESTING_TRUE_INSTANCE)).toBeTrue());
-        });
-      });
-    });
-});
diff --git a/src/guard/test/guard-class.spec.ts b/src/guard/test/guard-class.spec.ts
deleted file mode 100644
index b844ee85..00000000
--- a/src/guard/test/guard-class.spec.ts
+++ /dev/null
@@ -1,49 +0,0 @@
-// Object.
-import { guard } from '../lib/guard.object';
-// Function.
-import { guardClass } from '../lib/guard-class.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_FUNCTION,
-  TestingPerson
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.class.describe,
-  tests.guard.class.it
-);
-/**
- * Tests.
- */
-testing.describe(guardClass.name, () => {
-  testing
-  .it('is DEFINED', () => expect(guardClass).toBeDefined())
-  .it('with callback and payload', () => {
-    guardClass(TestingPerson, (result, value, payload) => {
-      expect(result).toBeTrue();
-      expect(value).toEqual(TestingPerson);
-      if (payload) {
-        expect(payload.action).toEqual('action');
-        expect(payload.name).toEqual('name');
-        expect(payload.param).toEqual('param');
-      }
-      return result;
-    }, { action: 'action', name: 'name', param: 'param' });
-  })
-  .it(`Class`, () => {
-    expect(guardClass(TestingPerson)).toBeTrue();
-    expect(guard.class(TestingPerson)).toBeTrue();
-  })
-  .it(`FUNCTION`, () => {
-    expect(guardClass(TESTING_FUNCTION)).toBeFalse();
-    expect(guard.class(TESTING_FUNCTION)).toBeFalse();
-  });
-});
diff --git a/src/guard/test/guard-date.spec.ts b/src/guard/test/guard-date.spec.ts
deleted file mode 100644
index d3c595a5..00000000
--- a/src/guard/test/guard-date.spec.ts
+++ /dev/null
@@ -1,74 +0,0 @@
-// Function.
-import { guardDate } from '../lib/guard-date.func';
-// Object.
-import { guard } from '../lib/guard.object';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_DATE,
-  TESTING_FUNCTION,
-
-  // Class.
-  TestingPerson
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.date.describe,
-  tests.guard.date.it
-);
-/**
- * Tests.
- */
-testing.describe(guardDate.name, () => {
-  let guardSpy: any;
-  testing
-    .it('is DEFINED', () => expect(guardDate).toBeDefined());
-
-  beforeEach(() => guardSpy = { ...{}, ...guard });
-  testing
-  .it('with callback and payload', () => {
-    guardDate(TESTING_DATE, (result, value, payload) => {
-      expect(result).toBeTrue();
-      expect(value).toEqual(TESTING_DATE);
-      if (payload) {
-        expect(payload.action).toEqual('action');
-        expect(payload.name).toEqual('name');
-        expect(payload.param).toEqual('param');
-      }
-      return result;
-    }, { action: 'action', name: 'name', param: 'param' });
-  })
-  .it(`called with ${TESTING_DATE}`, () => {
-      spyOn(guardSpy, 'date').withArgs(TESTING_DATE).and.returnValue(true);
-      guardSpy.date(TESTING_DATE);
-      expect(guardSpy.date).toHaveBeenCalled();
-  })
-  .it(`guard new Date()`, () => {
-    expect(guardDate(new Date('December 17, 1995 03:24:00'))).toBeTrue();
-    expect(guardDate(new Date('1995-12-17T03:24:00'))).toBeTrue();
-    expect(guardDate(new Date(1995, 11, 17))).toBeTrue();
-    expect(guardDate(new Date(1995, 11, 17, 3, 24, 0))).toBeTrue();
-    expect(guardDate(new Date(628021800000))).toBeTrue();
-    expect(guardDate(new Date(98, 1))).toBeTrue();
-    expect(guardDate(new Date(22, 1))).toBeTrue();
-
-    expect(guard.date(new Date('December 17, 1995 03:24:00'))).toBeTrue();
-    expect(guard.date(new Date('1995-12-17T03:24:00'))).toBeTrue();
-    expect(guard.date(new Date(1995, 11, 17))).toBeTrue();
-    expect(guard.date(new Date(1995, 11, 17, 3, 24, 0))).toBeTrue();
-    expect(guard.date(new Date(628021800000))).toBeTrue();
-    expect(guard.date(new Date(98, 1))).toBeTrue();
-    expect(guard.date(new Date(22, 1))).toBeTrue();
-  })
-  .it(`guard new Date() false`, () => {
-    expect(guardDate(new Date('invalid date'))).toBeFalse();
-    expect(guard.date(new Date('invalid date'))).toBeFalse();
-  });
-});
diff --git a/src/guard/test/guard-defined.spec.ts b/src/guard/test/guard-defined.spec.ts
deleted file mode 100644
index 3b36ebee..00000000
--- a/src/guard/test/guard-defined.spec.ts
+++ /dev/null
@@ -1,45 +0,0 @@
-// Function.
-import { guardDefined } from '../lib/guard-defined.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.defined.describe,
-  tests.guard.defined.it
-);
-/**
- * Tests.
- */
-testing.describe(guardDefined.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardDefined).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('with callback and payload', () => {
-      guardDefined(TESTING_STRING, (result, value, payload) => {
-        expect(result).toBeTrue();
-        expect(value).toEqual(TESTING_STRING);
-        if (payload) {
-          expect(payload.action).toEqual('action');
-          expect(payload.name).toEqual('name');
-          expect(payload.param).toEqual('param');
-        }
-        return result;
-      }, { action: 'action', name: 'name', param: 'param' });
-    })
-    .it('undefined', () => expect(guardDefined(undefined as any)).toBeFalse());
-  });
-});
diff --git a/src/guard/test/guard-false.spec.ts b/src/guard/test/guard-false.spec.ts
deleted file mode 100644
index 6167a991..00000000
--- a/src/guard/test/guard-false.spec.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_TRUE,
-  TESTING_FALSE
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardFalse } from '../lib/guard-false.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.false.describe,
-  tests.guard.false.it
-);
-/**
- * Tests.
- */
-testing.describe(guardFalse.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardFalse).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('with callback and payload', () => {
-      guardFalse(TESTING_FALSE, (result, value, payload) => {
-        expect(result).toBe(TESTING_TRUE);
-        expect(value).toBeFalse();
-        if (payload) {
-          expect(payload.action).toEqual('action');
-          expect(payload.name).toEqual('name');
-          expect(payload.param).toEqual('param');
-        }
-        return result;
-      }, { action: 'action', name: 'name', param: 'param' });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () =>
-      testing
-        .it(`${TESTING_FALSE}`, () => expect(guardFalse(TESTING_FALSE)).toBeTrue())
-        .it(`${TESTING_TRUE}`, () => expect(guardFalse(TESTING_TRUE as any)).toBeFalse())
-    )
-
-    // ... object.
-    .describe(`object`, () =>
-      testing
-        .it(`new Boolean(${TESTING_TRUE})`, () => expect(guardFalse(new Boolean(TESTING_TRUE) as any)).toBeFalse())
-        .it(`new Boolean(${TESTING_FALSE})`, () => expect(guardFalse(new Boolean(TESTING_FALSE) as any)).toBeTrue())
-    );
-  });
-});
diff --git a/src/guard/test/guard-function.spec.ts b/src/guard/test/guard-function.spec.ts
deleted file mode 100644
index 55028f44..00000000
--- a/src/guard/test/guard-function.spec.ts
+++ /dev/null
@@ -1,42 +0,0 @@
-// Function.
-import { guardFunction } from '../lib/guard-function.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_FUNCTION,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardFalse } from '../lib/guard-false.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.function.describe,
-  tests.guard.function.it
-);
-/**
- * Tests.
- */
-testing.describe(guardFalse.name, () => {
-  testing
-  // TRUE
-  .it('is DEFINED', () => expect(guardFunction).toBeDefined())
-  .it('with callback and payload', () => {
-    guardFunction(TESTING_FUNCTION, (result, value, payload) => {
-      expect(result).toBeTrue();
-      expect(value).toEqual(TESTING_FUNCTION);
-      if (payload) {
-        expect(payload.action).toEqual('action');
-        expect(payload.name).toEqual('name');
-        expect(payload.param).toEqual('param');
-      }
-      return result;
-    }, { action: 'action', name: 'name', param: 'param' });
-  })
-  .it(`function | Function`, () => expect(guardFunction(TESTING_FUNCTION)).toBeTrue());
-});
diff --git a/src/guard/test/guard-instance.spec.ts b/src/guard/test/guard-instance.spec.ts
deleted file mode 100644
index 09c26634..00000000
--- a/src/guard/test/guard-instance.spec.ts
+++ /dev/null
@@ -1,89 +0,0 @@
-// Function.
-import { guardInstance } from '../lib/guard-instance.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_FALSE_INSTANCE,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_FUNCTION_CONSTRUCTOR_PERSON,
-  TESTING_PERSON,
-
-  // Class.
-  TestingClass,
-  TestingPerson,
-  TestingPersonShape
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.instance.describe,
-  tests.guard.instance.it
-);
-/**
- * Tests.
- */
-testing.describe(guardInstance.name, () => {
-  const personInstance: TestingPersonShape = new (TESTING_FUNCTION_CONSTRUCTOR_PERSON as any)('First name', 'Sur name', 27);
-
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardInstance).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('callback', () => {
-      guardInstance(TESTING_CLASS, TestingClass, (result, value, payload) => {
-        expect(result).toBeTrue();
-        if (payload) {
-          expect(value).toEqual(TESTING_CLASS);
-        }
-        return result;
-      });
-    })
-    // ... instance.
-    .describe(`instance`, () => {
-      testing
-      .it(`CLASS`, () => expect(guardInstance(TESTING_CLASS, TestingClass)).toBeTrue())
-      .it(`class TestingPerson`, () => expect(guardInstance(TESTING_PERSON, TestingPerson)).toBeTrue())
-      .it(`function`, () => expect(guardInstance(personInstance, TESTING_FUNCTION_CONSTRUCTOR_PERSON as any)).toBeTrue());
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(guardInstance(TESTING_TRUE_INSTANCE, Boolean)).toBeTrue())
-        .it(`${TESTING_FALSE_INSTANCE}`, () => expect(guardInstance(TESTING_FALSE_INSTANCE, Boolean)).toBeTrue());
-      })
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`Number(${TESTING_NUMBER})`, () => expect(guardInstance(TESTING_NUMBER_CONSTRUCTOR, Number)).toBeFalse())
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(guardInstance(TESTING_NUMBER_INSTANCE, Number)).toBeTrue());
-      })
-
-      // string
-      .describe(`string`, () => {
-        it(`String(${TESTING_STRING})`, () => expect(guardInstance(TESTING_STRING_CONSTRUCTOR, String)).toBeFalse());
-        it(`new String(${TESTING_STRING})`, () => expect(guardInstance(TESTING_STRING_INSTANCE, String)).toBeTrue());
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-key.spec.ts b/src/guard/test/guard-key.spec.ts
deleted file mode 100644
index bc1f433f..00000000
--- a/src/guard/test/guard-key.spec.ts
+++ /dev/null
@@ -1,61 +0,0 @@
-// Function.
-import { guardKey } from '../lib/guard-key.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_NUMBER,
-  TESTING_STRING,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.key.describe,
-  tests.guard.key.it
-);
-/**
- * Tests.
- */
-testing.describe(guardKey.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardKey).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('with callback and payload', () => {
-      guardKey(TESTING_NUMBER, (result, value, payload) => {
-        expect(result).toBeTrue();
-        expect(value).toEqual(TESTING_NUMBER);
-        if (payload) {
-          expect(payload.action).toEqual('action');
-          expect(payload.name).toEqual('name');
-          expect(payload.param).toEqual('param');
-        }
-        return result;
-      }, { action: 'action', name: 'name', param: 'param' });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // number
-      .describe(`number`, () => it(`${TESTING_NUMBER}`, () => expect(guardKey(TESTING_NUMBER)).toBeTrue()))
-      // string
-      .describe(`string`, () => it(`${TESTING_STRING}`, () => expect(guardKey(TESTING_STRING)).toBeTrue()))
-      // symbol
-      .describe(`symbol`, () => {
-        it(`Symbol(${TESTING_NUMBER})`, () => expect(guardKey(TESTING_SYMBOL_NUMBER)).toBeTrue());
-        it(`Symbol(${TESTING_STRING})`, () => expect(guardKey(TESTING_SYMBOL_STRING)).toBeTrue());
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-null.spec.ts b/src/guard/test/guard-null.spec.ts
deleted file mode 100644
index 1640b51d..00000000
--- a/src/guard/test/guard-null.spec.ts
+++ /dev/null
@@ -1,48 +0,0 @@
-// Function.
-import { guardNull } from '../lib/guard-null.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_NULL,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.null.describe,
-  tests.guard.null.it
-);
-/**
- * Tests.
- */
-testing.describe(guardNull.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardNull).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () => {
-
-      testing
-      .it('with callback and payload', () => {
-        guardNull(TESTING_NULL, (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(TESTING_NULL);
-          if (payload) {
-            expect(payload.action).toEqual('action');
-            expect(payload.name).toEqual('name');
-            expect(payload.param).toEqual('param');
-          }
-          return result;
-        }, { action: 'action', name: 'name', param: 'param' });
-      })
-
-      // ... primitives.
-      .describe(`primitive`, () => testing.it(`${TESTING_NULL}`, () => expect(guardNull(TESTING_NULL)).toBeTrue()));
-    });
-});
diff --git a/src/guard/test/guard-number-between.spec.ts b/src/guard/test/guard-number-between.spec.ts
deleted file mode 100644
index 940daff9..00000000
--- a/src/guard/test/guard-number-between.spec.ts
+++ /dev/null
@@ -1,54 +0,0 @@
-// Function.
-import { guardNumberBetween } from '../lib/guard-number-between.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_NUMBER,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.numberBetween.describe,
-  tests.guard.numberBetween.it
-);
-/**
- * Tests.
- */
-testing.describe(guardNumberBetween.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardNumberBetween).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('with callback and payload', () => {
-      guardNumberBetween(TESTING_NUMBER, 1, TESTING_NUMBER, (result, value, payload) => {
-        expect(result).toBeTrue();
-        expect(value).toEqual(TESTING_NUMBER);
-        if (payload) {
-          expect(payload.action).toEqual('action');
-          expect(payload.name).toEqual('name');
-          expect(payload.param).toEqual('param');
-        }
-        return result;
-      }, { action: 'action', name: 'name', param: 'param' });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(guardNumberBetween(TESTING_NUMBER, 1, TESTING_NUMBER)).toBeTrue());
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-number.spec.ts b/src/guard/test/guard-number.spec.ts
deleted file mode 100644
index 4aaa18bf..00000000
--- a/src/guard/test/guard-number.spec.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-// Function.
-import { guardNumber } from '../lib/guard-number.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.number.describe,
-  tests.guard.number.it
-);
-/**
- * Tests.
- */
-testing.describe(guardNumber.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardNumber).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('with callback and payload', () => {
-      guardNumber(TESTING_NUMBER, (result, value, payload) => {
-        expect(result).toBeTrue();
-        expect(value).toEqual(TESTING_NUMBER);
-        if (payload) {
-          expect(payload.action).toEqual('action');
-          expect(payload.name).toEqual('name');
-          expect(payload.param).toEqual('param');
-        }
-        return result;
-      }, { action: 'action', name: 'name', param: 'param' });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // number
-      .describe(`number`, () =>
-        testing
-          .it(`${TESTING_NUMBER}`, () => expect(guardNumber(TESTING_NUMBER)).toBeTrue())
-          .it(`${TESTING_NUMBER_CONSTRUCTOR}`, () => expect(guardNumber(TESTING_NUMBER_CONSTRUCTOR)).toBeTrue()))
-      // number object
-      .describe(`number object`, () =>
-        testing.it(`${TESTING_NUMBER_INSTANCE}`, () => expect(guardNumber(TESTING_NUMBER_INSTANCE)).toBeTrue()));
-    });
-  });
-});
diff --git a/src/guard/test/guard-object-key-in.spec.ts b/src/guard/test/guard-object-key-in.spec.ts
deleted file mode 100644
index cb29df56..00000000
--- a/src/guard/test/guard-object-key-in.spec.ts
+++ /dev/null
@@ -1,96 +0,0 @@
-// Function.
-import { guardObjectKeyIn } from '../lib/guard-object-key-in.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_NUMBER,
-  TESTING_OBJECT,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.objectKeyIn.describe,
-  tests.guard.objectKeyIn.it
-);
-/**
- * Tests.
- */
-testing.describe(guardObjectKeyIn.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardObjectKeyIn).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('with callback and payload', () => {
-      guardObjectKeyIn(TESTING_CLASS, 'firstName', (result, value, payload) => {
-        expect(result).toBeTrue();
-        expect(value).toEqual(TESTING_CLASS);
-        if (payload) {
-          expect(payload.action).toEqual('action');
-          expect(payload.name).toEqual('name');
-          expect(payload.param).toEqual('param');
-        }
-        return result;
-      }, { action: 'action', name: 'name', param: 'param' });
-    })
-
-    // ... instance.
-    .describe(`instance`, () => {
-      testing.describe(`CLASS`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectKeyIn(TESTING_CLASS, 1030405027)).toBeTrue();
-          expect(guardObjectKeyIn(TESTING_CLASS, 5)).toBeTrue();
-        })
-
-        .it('finds getter number', () => expect(guardObjectKeyIn(TESTING_CLASS, TESTING_NUMBER)).toBeTrue())
-
-        // string.
-        .it('has string key', () => expect(guardObjectKeyIn(TESTING_CLASS, 'surname')).toBeTrue())
-
-        // symbol.
-        .it('finds getter symbol key', () => {
-          expect(guardObjectKeyIn(TESTING_CLASS, TESTING_SYMBOL_NUMBER)).toBeTrue();
-          expect(guardObjectKeyIn(TESTING_CLASS, TESTING_SYMBOL_STRING)).toBeTrue();
-        });
-      });
-    })
-
-    // ... objects.
-    .describe('object', () => {
-      testing.describe(`OBJECT_ONE`, () => {
-        testing
-          // number.
-          .it('has number key', () => {
-            expect(guardObjectKeyIn(TESTING_OBJECT, 1030405027)).toBeTrue();
-            expect(guardObjectKeyIn(TESTING_OBJECT, 5)).toBeTrue();
-            expect(guardObjectKeyIn(TESTING_OBJECT, TESTING_NUMBER)).toBeTrue();
-          })
-
-          // string.
-          .it('has string key', () => {
-            expect(guardObjectKeyIn(TESTING_OBJECT, 'key as string')).toBeTrue();
-            expect(guardObjectKeyIn(TESTING_OBJECT, 'x')).toBeTrue();
-          })
-
-          // symbol.
-          .it('has symbol key', () => {
-            expect(guardObjectKeyIn(TESTING_OBJECT, TESTING_NUMBER)).toBeTrue();
-            expect(guardObjectKeyIn(TESTING_OBJECT, TESTING_SYMBOL_STRING)).toBeTrue();
-          });
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-object-key.spec.ts b/src/guard/test/guard-object-key.spec.ts
deleted file mode 100644
index 6ce81630..00000000
--- a/src/guard/test/guard-object-key.spec.ts
+++ /dev/null
@@ -1,93 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_NUMBER,
-  TESTING_OBJECT,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardObjectKey } from '../lib/guard-object-key.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.objectKey.describe,
-  tests.guard.objectKey.it
-);
-/**
- * Tests.
- */
-testing.describe(guardObjectKey.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardObjectKey).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('callback', () => {
-      guardObjectKey(TESTING_CLASS, 'firstName', (result, value, payload) => {
-        expect(result).toBeTrue();
-        if (payload) {
-          expect(value).toEqual(TESTING_CLASS);
-        }
-        return result;
-      });
-    })
-
-    // ... instance.
-    .describe(`instance`, () => {
-      testing.describe(`CLASS`, () => {
-        // number.
-        it('has number key', () => {
-          expect(guardObjectKey(TESTING_CLASS, 1030405027)).toBeTrue();
-          expect(guardObjectKey(TESTING_CLASS, 5)).toBeTrue();
-        });
-
-        it('finds getter number', () => expect(guardObjectKey(TESTING_CLASS, TESTING_NUMBER)).toBe(TESTING_FALSE));
-
-        // string.
-        it('has string key', () => expect(guardObjectKey(TESTING_CLASS, 'surname')).toBeTrue());
-
-        // symbol.
-        it('finds getter symbol key', () => {
-          expect(guardObjectKey(TESTING_CLASS, TESTING_SYMBOL_NUMBER)).toBe(TESTING_FALSE);
-          expect(guardObjectKey(TESTING_CLASS, TESTING_SYMBOL_STRING)).toBe(TESTING_FALSE);
-        });
-      });
-    })
-
-    // ... objects.
-    .describe('object', () => {
-      testing.describe(`OBJECT_ONE`, () => {
-        testing
-          // number.
-          .it('has number key', () => {
-            expect(guardObjectKey(TESTING_OBJECT, 1030405027)).toBeTrue();
-            expect(guardObjectKey(TESTING_OBJECT, 5)).toBeTrue();
-            expect(guardObjectKey(TESTING_OBJECT, TESTING_NUMBER)).toBeTrue();
-          })
-
-          // string.
-          .it('has string key', () => {
-            expect(guardObjectKey(TESTING_OBJECT, 'key as string')).toBeTrue();
-            expect(guardObjectKey(TESTING_OBJECT, 'x')).toBeTrue();
-          })
-
-          // symbol.
-          .it('has symbol key', () => {
-            expect(guardObjectKey(TESTING_OBJECT, TESTING_NUMBER)).toBeTrue();
-            expect(guardObjectKey(TESTING_OBJECT, TESTING_SYMBOL_STRING)).toBeTrue();
-          });
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-object-keys-in.spec.ts b/src/guard/test/guard-object-keys-in.spec.ts
deleted file mode 100644
index 8ebab17c..00000000
--- a/src/guard/test/guard-object-keys-in.spec.ts
+++ /dev/null
@@ -1,108 +0,0 @@
-// Function.
-import { guardObjectKeysIn } from '../lib/guard-object-keys-in.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_NUMBER,
-  TESTING_OBJECT,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.objectKeysIn.describe,
-  tests.guard.objectKeysIn.it
-);
-/**
- * Tests.
- */
-testing.describe(guardObjectKeysIn.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardObjectKeysIn).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    // ... instance.
-    .describe(`instance`, () => {
-      testing.describe(`TESTING_CLASS`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectKeysIn(TESTING_CLASS, [1030405027])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_CLASS, [5])).toBeTrue();
-        })
-
-        .it('finds getter number', () => expect(guardObjectKeysIn(TESTING_CLASS, [TESTING_NUMBER])).toBeTrue())
-
-        // string.
-        .it('has string key', () => expect(guardObjectKeysIn(TESTING_CLASS, ['surname'])).toBeTrue())
-
-        // symbol.
-        .it('finds getter symbol key', () => {
-          expect(guardObjectKeysIn(TESTING_CLASS, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_CLASS, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    })
-
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .describe(`TESTING_OBJECT`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectKeysIn(TESTING_OBJECT, [1030405027])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, [5])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue();
-        })
-
-        // string.
-        .it('has string key', () => {
-          expect(guardObjectKeysIn(TESTING_OBJECT, ['key as string'])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, ['x'])).toBeTrue();
-        })
-
-        // symbol.
-        .it('has symbol key', () => {
-          expect(guardObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    })
-
-    .describe('object with some and every key', () => {
-      testing.describe(`TESTING_OBJECT`, () => {
-        testing
-        // number.
-        .it('has number key or any key', () => {
-          expect(guardObjectKeysIn(TESTING_OBJECT, [1030405027, 'key as string'])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, [5])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue();
-        })
-
-        // string.
-        .it('has string key', () => {
-          expect(guardObjectKeysIn(TESTING_OBJECT, ['key as string'])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, ['x'])).toBeTrue();
-        })
-
-        // symbol.
-        .it('has symbol key', () => {
-          expect(guardObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-          expect(guardObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-object-keys.spec.ts b/src/guard/test/guard-object-keys.spec.ts
deleted file mode 100644
index 43a6a77d..00000000
--- a/src/guard/test/guard-object-keys.spec.ts
+++ /dev/null
@@ -1,108 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_NUMBER,
-  TESTING_OBJECT,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardObjectKeys } from '../lib/guard-object-keys.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.objectKeys.describe,
-  tests.guard.objectKeys.it
-);
-/**
- * Tests.
- */
-testing.describe(guardObjectKeys.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardObjectKeys).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    // ... instance.
-    .describe(`instance`, () => {
-      testing.describe(`TESTING_CLASS`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectKeys(TESTING_CLASS, [1030405027])).toBeTrue();
-          expect(guardObjectKeys(TESTING_CLASS, [5])).toBeTrue();
-        })
-
-        .it('finds getter number', () => expect(guardObjectKeys(TESTING_CLASS, [TESTING_NUMBER])).toBeFalse())
-
-        // string.
-        .it('has string key', () => expect(guardObjectKeys(TESTING_CLASS, ['surname'])).toBeTrue())
-
-        // symbol.
-        .it('finds getter symbol key', () => {
-          expect(guardObjectKeys(TESTING_CLASS, [TESTING_SYMBOL_NUMBER])).toBeFalse();
-          expect(guardObjectKeys(TESTING_CLASS, [TESTING_SYMBOL_STRING])).toBeFalse();
-        });
-      });
-    })
-
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .describe(`TESTING_OBJECT`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectKeys(TESTING_OBJECT, [1030405027])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, [5])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue();
-        })
-
-        // string.
-        .it('has string key', () => {
-          expect(guardObjectKeys(TESTING_OBJECT, ['key as string'])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, ['x'])).toBeTrue();
-        })
-
-        // symbol.
-        .it('has symbol key', () => {
-          expect(guardObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    })
-
-    .describe('object with some and every key', () => {
-      testing.describe(`TESTING_OBJECT`, () => {
-        testing
-        // number.
-        .it('has number key or any key', () => {
-          expect(guardObjectKeys(TESTING_OBJECT, [1030405027, 'key as string'])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, [5])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue();
-        })
-
-        // string.
-        .it('has string key', () => {
-          expect(guardObjectKeys(TESTING_OBJECT, ['key as string'])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, ['x'])).toBeTrue();
-        })
-
-        // symbol.
-        .it('has symbol key', () => {
-          expect(guardObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-          expect(guardObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-object-some-keys.spec.ts b/src/guard/test/guard-object-some-keys.spec.ts
deleted file mode 100644
index 18ddf202..00000000
--- a/src/guard/test/guard-object-some-keys.spec.ts
+++ /dev/null
@@ -1,110 +0,0 @@
-// Function.
-import { guardObjectSomeKeys } from '../lib/guard-object-some-keys.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_NUMBER,
-  TESTING_OBJECT,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.objectSomeKeys.describe,
-  tests.guard.objectSomeKeys.it
-);
-/**
- * Tests.
- */
-testing.describe(guardObjectSomeKeys.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardObjectSomeKeys).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    // ... instance.
-    .describe(`instance`, () => {
-      testing
-      .describe(`TESTING_CLASS`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectSomeKeys(TESTING_CLASS, [1030405027])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_CLASS, [5])).toBeTrue();
-        })
-
-        .it('finds getter number', () => expect(guardObjectSomeKeys(TESTING_CLASS, [TESTING_NUMBER])).toBeFalse())
-
-        // string.
-        .it('has string key', () => expect(guardObjectSomeKeys(TESTING_CLASS, ['surname'])).toBeTrue())
-
-        // symbol.
-        .it('finds getter symbol key', () => {
-          expect(guardObjectSomeKeys(TESTING_CLASS, [TESTING_SYMBOL_NUMBER])).toBeFalse();
-          expect(guardObjectSomeKeys(TESTING_CLASS, [TESTING_SYMBOL_STRING])).toBeFalse();
-        });
-      });
-    })
-
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .describe(`TESTING_OBJECT`, () => {
-        testing
-        // number.
-        .it('has number key', () => {
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [1030405027])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [5])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue();
-        })
-
-        // string.
-        .it('has string key', () => {
-          expect(guardObjectSomeKeys(TESTING_OBJECT, ['key as string'])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, ['x'])).toBeTrue();
-        })
-
-        // symbol.
-        .it('has symbol key', () => {
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    })
-
-    .describe('object with some and every key', () => {
-      testing
-      .describe(`TESTING_OBJECT`, () => {
-        testing
-        // number.
-        .it('has number key or any key', () => {
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [1030405027, [5, TESTING_NUMBER]])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [[TESTING_NUMBER], [5]])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue();
-        })
-
-        // string.
-        .it('has string key', () => {
-          expect(guardObjectSomeKeys(TESTING_OBJECT, ['key as string', ['!@#$%^&*()Company', 'x']])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [['x', '!@#$%^&*()Company'], 'key as string'])).toBeTrue();
-        })
-
-        // symbol.
-        .it('has symbol key', () => {
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING]])).toBeTrue();
-          expect(guardObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-        });
-      });
-    });
-  });
-});
diff --git a/src/guard/test/guard-object.spec.ts b/src/guard/test/guard-object.spec.ts
deleted file mode 100644
index 9f45bd1a..00000000
--- a/src/guard/test/guard-object.spec.ts
+++ /dev/null
@@ -1,51 +0,0 @@
-// Function.
-import { guardObject } from '../lib/guard-object.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_OBJECT,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.object.describe,
-  tests.guard.object.it
-);
-/**
- * Tests.
- */
-testing.describe(guardObject.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardObject).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('callback', () => {
-      guardObject(TESTING_OBJECT, (result, value, payload) => {
-        expect(result).toBeTrue();
-        if (payload) {
-          expect(value).toEqual(TESTING_OBJECT);
-        }
-        return result;
-      });
-    })
-
-    // ... objects.
-    .describe('object', () => {
-      testing
-        .it(`CLASS`, () => expect(guardObject(TESTING_CLASS)).toBeTrue())
-        .it(`OBJECT_ONE`, () => expect(guardObject(TESTING_OBJECT)).toBeTrue())
-        .it(`TESTING_DATE`, () => expect(guardObject(TESTING_DATE)).toBeTrue());
-    });
-  });
-});
diff --git a/src/guard/test/guard-primitive.spec.ts b/src/guard/test/guard-primitive.spec.ts
deleted file mode 100644
index 21776fc1..00000000
--- a/src/guard/test/guard-primitive.spec.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-// Function.
-import { guardPrimitive } from '../lib/guard-primitive.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_FALSE,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_STRING,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_UNDEFINED,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.primitive.describe,
-  tests.guard.primitive.it
-);
-/**
- * Tests.
- */
-testing.describe(guardPrimitive.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardPrimitive).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing
-    .it('callback', () => {
-      guardPrimitive<string>(TESTING_STRING, 'string' , (result, value, payload) => {
-        expect(result).toBeTrue();
-        if (payload) {
-          expect(value).toEqual(TESTING_STRING);
-        }
-        return result;
-      });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => it(`${TESTING_BIGINT}`, () => expect(guardPrimitive(TESTING_BIGINT, 'bigint')).toBeTrue()))
-
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(guardPrimitive(TESTING_TRUE, 'boolean')).toBeTrue())
-        .it(`${TESTING_FALSE}`, () => expect(guardPrimitive(TESTING_FALSE, 'boolean')).toBeTrue());
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(guardPrimitive(TESTING_NULL, 'null')).toBeTrue())
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(guardPrimitive(TESTING_NUMBER, 'number')).toBeTrue());
-      })
-
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(guardPrimitive(TESTING_STRING, 'string')).toBeTrue());
-      })
-
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(guardPrimitive(TESTING_SYMBOL_NUMBER, 'symbol')).toBeTrue())
-        .it(`Symbol(${TESTING_STRING})`, () => expect(guardPrimitive(TESTING_SYMBOL_STRING, 'symbol')).toBeTrue());
-      })
-
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(guardPrimitive(TESTING_UNDEFINED, 'undefined')).toBeTrue());
-    });
-  });
-});
diff --git a/src/guard/test/guard-regexp.spec.ts b/src/guard/test/guard-regexp.spec.ts
deleted file mode 100644
index e4b2b860..00000000
--- a/src/guard/test/guard-regexp.spec.ts
+++ /dev/null
@@ -1,52 +0,0 @@
-// Function.
-import { guardRegExp } from '../lib/guard-regexp.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_TRUE,
-  TESTING_REGEXP
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.regexp.describe,
-  tests.guard.regexp.it
-);
-/**
- * Tests.
- */
-testing.describe(guardRegExp.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardRegExp).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () => {
-      testing
-      .it('with callback and payload', () => {
-        guardRegExp(TESTING_REGEXP, (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(TESTING_REGEXP);
-          if (payload) {
-            expect(payload.action).toEqual('action');
-            expect(payload.name).toEqual('name');
-            expect(payload.param).toEqual('param');
-          }
-          return result;
-        }, { action: 'action', name: 'name', param: 'param' });
-      })
-
-      // ... primitives.
-      .describe(`primitive`, () => {
-        testing
-          // bigint
-          .describe(`RegExp`, () => it(`${TESTING_REGEXP}`, () => expect(guardRegExp(TESTING_REGEXP)).toBe(TESTING_TRUE)));
-      });
-    });
-});
diff --git a/src/guard/test/guard-string-includes-some.spec.ts b/src/guard/test/guard-string-includes-some.spec.ts
deleted file mode 100644
index 4988da11..00000000
--- a/src/guard/test/guard-string-includes-some.spec.ts
+++ /dev/null
@@ -1,87 +0,0 @@
-// Function.
-import { guardStringIncludesSome } from '../lib/guard-string-includes-some.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringIncludesSome.describe,
-  tests.is.stringIncludesSome.it
-);
-/**
- * Tests.
- */
-testing.describe(guardStringIncludesSome.name, () => {
-  const TESTING_STRING_LONG = `Lorem Ipsum is simply dummy text of the printing and typesetting industry.
-  Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,
-  when an unknown printer took a galley of type and scrambled it to make a type specimen book.
-  It has survived not only five centuries, but also the leap into electronic typesetting,
-  remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset
-  sheets containing Lorem Ipsum passages, and more recently with desktop publishing software
-  like Aldus PageMaker including versions of Lorem Ipsum.`;
-
-  const TESTING_STRING_LONG_INSTANCE = new String(TESTING_STRING_LONG);
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardStringIncludesSome).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          guardStringIncludesSome(TESTING_STRING, ['Company'], (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`TESTING_STRING, TESTING_STRING_LONG`, () => {
-                  expect(guardStringIncludesSome(TESTING_STRING, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeTrue();
-                    // No word exists.
-                  expect(guardStringIncludesSome(TESTING_STRING_LONG, [
-                    'no text',
-                    'no text is here'
-                  ])).toBeFalse();
-
-                  // Every word exists.
-                  expect(guardStringIncludesSome(TESTING_STRING_LONG_INSTANCE, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                  ])).toBeTrue();
-
-                  // Some word exists.
-                  expect(guardStringIncludesSome(TESTING_STRING_LONG, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                    'no text is here'
-                  ])).toBeTrue();
-                })
-                .it(`String(${TESTING_STRING})`, () =>
-                  expect(guardStringIncludesSome(TESTING_STRING_CONSTRUCTOR, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeTrue());
-            });
-        });
-    });
-});
\ No newline at end of file
diff --git a/src/guard/test/guard-string-includes.spec.ts b/src/guard/test/guard-string-includes.spec.ts
deleted file mode 100644
index 1f00f236..00000000
--- a/src/guard/test/guard-string-includes.spec.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-// Function.
-import { guardStringIncludes } from '../lib/guard-string-includes.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.stringIncludes.describe,
-  tests.guard.stringIncludes.it
-);
-/**
- * Tests.
- */
-testing.describe(guardStringIncludes.name, () => {
-  const TESTING_STRING_LONG = `Lorem Ipsum is simply dummy text of the printing and typesetting industry.
-  Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,
-  when an unknown printer took a galley of type and scrambled it to make a type specimen book.
-  It has survived not only five centuries, but also the leap into electronic typesetting,
-  remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset
-  sheets containing Lorem Ipsum passages, and more recently with desktop publishing software
-  like Aldus PageMaker including versions of Lorem Ipsum.`;
-
-  const TESTING_STRING_LONG_INSTANCE = new String(TESTING_STRING_LONG);
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardStringIncludes).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          guardStringIncludes(TESTING_STRING, ['Company'], (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => {
-                  expect(guardStringIncludes(TESTING_STRING, ['Company'])).toBeTrue();
-                  expect(guardStringIncludes(TESTING_STRING, [TESTING_STRING, '!@#$%^&*()'])).toBeTrue();
-                    // No word exists.
-                  expect(guardStringIncludes(TESTING_STRING_LONG, [
-                    'no text',
-                    'no text is here'
-                  ])).toBeFalse();
-
-                  // Every word exists.
-                  expect(guardStringIncludes(TESTING_STRING_LONG_INSTANCE, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                  ])).toBeTrue();
-
-                  // Some word exists.
-                  expect(guardStringIncludes(TESTING_STRING_LONG, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                    'no text is here'
-                  ])).toBeFalse();
-                })
-                .it(`String(${TESTING_STRING})`, () =>
-                  expect(guardStringIncludes(TESTING_STRING_CONSTRUCTOR, [TESTING_STRING, '!@#$%^&*()'])).toBeTrue());
-            });
-        });
-    });
-});
diff --git a/src/guard/test/guard-string-length-between.spec.ts b/src/guard/test/guard-string-length-between.spec.ts
deleted file mode 100644
index dd7661f6..00000000
--- a/src/guard/test/guard-string-length-between.spec.ts
+++ /dev/null
@@ -1,86 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardStringLengthBetween } from '../lib/guard-string-length-between.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.stringLengthBetween.describe,
-  tests.guard.stringLengthBetween.it
-);
-/**
- * Tests.
- */
-testing.describe(`guardStringLengthBetween()`, () => {
-  // Defined.
-  testing
-    .it('is DEFINED', () => expect(guardStringLengthBetween).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () =>
-      testing
-        .it('with callback and payload', () => {
-          guardStringLengthBetween(TESTING_STRING, 3, 1000, (result, value, payload) => {
-            expect(result).toBeTrue();
-            expect(value).toEqual(TESTING_STRING);
-            if (payload) {
-              expect(payload.action).toEqual('action');
-              expect(payload.name).toEqual('name');
-              expect(payload.param).toEqual('param');
-            }
-            return result;
-          }, { action: 'action', name: 'name', param: 'param' });
-        })
-
-        // ... primitives.
-        .describe(`primitive`, () =>
-          testing
-            .describe(`string`, () =>
-              testing
-                .it(`${TESTING_STRING} minimum 3`, () =>
-                  expect(guardStringLengthBetween(TESTING_STRING, 3, 1000)).toBeTrue()
-                )
-                .it(`${TESTING_STRING} maximum 3`, () =>
-                  expect(guardStringLengthBetween(TESTING_STRING, 0, 3)).toBeFalse()
-                )
-            )
-            .it(`${TESTING_STRING} minimum 18`, () =>
-              expect(guardStringLengthBetween(TESTING_STRING, 18, 1000)).toBeFalse()
-            )
-            .it(`${TESTING_STRING} maximum 17`, () =>
-              expect(guardStringLengthBetween(TESTING_STRING, 0, 17)).toBeTrue()
-            )
-            .it(`${TESTING_STRING} minimum 5 maximum 21`, () =>
-              expect(guardStringLengthBetween(TESTING_STRING, 5, 21)).toBeTrue()
-            )
-        )
-    )
-    .describe(`String`, () =>
-      testing
-        .it(`new String(${TESTING_STRING}) minimum 3`, () =>
-          expect(guardStringLengthBetween(TESTING_STRING_INSTANCE, 3, 1000)).toBeTrue()
-        )
-        .it(`new String(${TESTING_STRING}) maximum 3`, () =>
-          expect(guardStringLengthBetween(TESTING_STRING_INSTANCE, 0, 3)).toBeFalse()
-        )
-        .it(`new String(${TESTING_STRING}) minimum 18`, () =>
-          expect(guardStringLengthBetween(TESTING_STRING_INSTANCE, 18, 1000)).toBeFalse()
-        )
-        .it(`new String(${TESTING_STRING}) maximum 17`, () =>
-          expect(guardStringLengthBetween(TESTING_STRING_INSTANCE, 0, 17)).toBeTrue()
-        )
-        .it(`new String(${TESTING_STRING}) minimum 5 maximum 21`, () =>
-          expect(guardStringLengthBetween(TESTING_STRING_INSTANCE, 5, 21)).toBeTrue()
-        )
-    );
-});
diff --git a/src/guard/test/guard-string-length.spec.ts b/src/guard/test/guard-string-length.spec.ts
deleted file mode 100644
index c3167ad0..00000000
--- a/src/guard/test/guard-string-length.spec.ts
+++ /dev/null
@@ -1,70 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardStringLength } from '../lib/guard-string-length.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.stringLength.describe,
-  tests.guard.stringLength.it
-);
-/**
- * Tests.
- */
-testing.describe(`guardStringLength()`, () => {
-  // Defined.
-  testing
-    .it('is DEFINED', () => expect(guardStringLength).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () =>
-      testing
-        .it('with callback and payload', () => {
-          guardStringLength(TESTING_STRING, 17, (result, value, payload) => {
-            expect(result).toBeTrue();
-            expect(value).toEqual(TESTING_STRING);
-            if (payload) {
-              expect(payload.action).toEqual('action');
-              expect(payload.name).toEqual('name');
-              expect(payload.param).toEqual('param');
-            }
-            return result;
-          }, { action: 'action', name: 'name', param: 'param' });
-        })
-
-        // ... primitives.
-        .describe(`primitive`, () =>
-          testing
-            .describe(`string`, () =>
-              testing
-                .it(`${TESTING_STRING}`, () =>
-                  expect(guardStringLength(TESTING_STRING, 17)).toBeTrue()
-                )
-                .it(`${TESTING_STRING}`, () =>
-                  expect(guardStringLength(TESTING_STRING, 16)).toBeFalse()
-                )
-                .it(`${TESTING_STRING}`, () =>
-                  expect(guardStringLength(TESTING_STRING, 18)).toBeFalse()
-                )
-            )
-        )
-    )
-    .describe(`String`, () =>
-      testing
-        .it(`new String(${TESTING_STRING})`, () =>
-          (expect(guardStringLength(TESTING_STRING_INSTANCE, 17)).toBeTrue(),
-          expect(guardStringLength(TESTING_STRING_INSTANCE, 16)).toBeFalse(),
-          expect(guardStringLength(TESTING_STRING_INSTANCE, 18)).toBeFalse())
-        )
-    );
-});
diff --git a/src/guard/test/guard-string.spec.ts b/src/guard/test/guard-string.spec.ts
deleted file mode 100644
index 02a0837e..00000000
--- a/src/guard/test/guard-string.spec.ts
+++ /dev/null
@@ -1,61 +0,0 @@
-// Function.
-import { guardString } from '../lib/guard-string.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.string.describe,
-  tests.guard.string.it
-);
-/**
- * Tests.
- */
-testing.describe(guardString.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardString).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () => {
-      testing
-        .it('with callback and payload', () => {
-          guardString(TESTING_STRING, (result, value, payload) => {
-            expect(result).toBeTrue();
-            expect(value).toEqual(TESTING_STRING);
-            if (payload) {
-              expect(payload.action).toEqual('action');
-              expect(payload.name).toEqual('name');
-              expect(payload.param).toEqual('param');
-            }
-            return result;
-          }, { action: 'action', name: 'name', param: 'param' });
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            .describe(`string`, () =>
-              testing.it(`${TESTING_STRING}`, () =>
-                expect(guardString(TESTING_STRING)).toBeTrue()
-              )
-            )
-            .describe(`object`, () =>
-              testing.describe(`String`, () =>
-                testing.it(`new String(${TESTING_STRING})`, () =>
-                  expect(guardString(TESTING_STRING_INSTANCE)).toBeTrue()
-                )
-              )
-            );
-        });
-    });
-});
diff --git a/src/guard/test/guard-symbol.spec.ts b/src/guard/test/guard-symbol.spec.ts
deleted file mode 100644
index 71a56e24..00000000
--- a/src/guard/test/guard-symbol.spec.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_NUMBER,
-  TESTING_STRING,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardSymbol } from '../lib/guard-symbol.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.symbol.describe,
-  tests.guard.symbol.it
-);
-/**
- * Tests.
- */
-testing.describe(guardSymbol.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardSymbol).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () => {
-      testing
-      .it('with callback and payload', () => {
-        guardSymbol(TESTING_SYMBOL_STRING, (result, value, payload) => {
-          expect(result).toBeTrue();
-          expect(value).toEqual(TESTING_SYMBOL_STRING);
-          if (payload) {
-            expect(payload.action).toEqual('action');
-            expect(payload.name).toEqual('name');
-            expect(payload.param).toEqual('param');
-          }
-          return result;
-        }, { action: 'action', name: 'name', param: 'param' });
-      })
-
-      // ... primitives.
-      .describe(`primitive`, () => {
-        testing
-          // symbol
-          .describe(`symbol`, () => {
-            testing
-              .it(`Symbol(${TESTING_NUMBER})`, () => expect(guardSymbol(TESTING_SYMBOL_NUMBER)).toBe(TESTING_TRUE))
-              .it(`Symbol(${TESTING_STRING})`, () => expect(guardSymbol(TESTING_SYMBOL_STRING)).toBe(TESTING_TRUE));
-          });
-      });
-    });
-});
diff --git a/src/guard/test/guard-true.spec.ts b/src/guard/test/guard-true.spec.ts
deleted file mode 100644
index a514f934..00000000
--- a/src/guard/test/guard-true.spec.ts
+++ /dev/null
@@ -1,55 +0,0 @@
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_TRUE,
-  TESTING_FALSE
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-import { guardTrue } from '../lib/guard-true.func';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.true.describe,
-  tests.guard.true.it
-);
-/**
- * Tests.
- */
-testing.describe(guardTrue.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(guardTrue).toBeDefined())
-
-  // Checks ...
-  .describe(`guards`, () => {
-    testing.it('callback', () => {
-      guardTrue(TESTING_TRUE, (result, value, payload) => {
-        expect(result).toBe(TESTING_TRUE);
-        if (payload) {
-          expect(value).toBeTrue();
-        }
-        return result;
-      });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () =>
-      testing
-        .it(`${TESTING_TRUE}`, () => expect(guardTrue(TESTING_TRUE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE}`, () => expect(guardTrue(TESTING_FALSE as any)).toBe(TESTING_FALSE))
-    )
-
-    // ... object.
-    .describe(`object`, () =>
-      testing
-        .it(`new Boolean(${TESTING_TRUE})`, () => expect(guardTrue(new Boolean(TESTING_TRUE) as any)).toBe(TESTING_TRUE))
-        .it(`new Boolean(${TESTING_FALSE})`, () => expect(guardTrue(new Boolean(TESTING_FALSE) as any)).toBe(TESTING_FALSE))
-    );
-  });
-});
diff --git a/src/guard/test/guard-type.spec.ts b/src/guard/test/guard-type.spec.ts
deleted file mode 100644
index 92b54d7d..00000000
--- a/src/guard/test/guard-type.spec.ts
+++ /dev/null
@@ -1,132 +0,0 @@
-// Function.
-import { guardType } from '../lib/guard-type.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-// Function.
-/**
- * Initialize testing.
- */
-const testing = new Testing(tests.is.type.describe, tests.is.type.it);
-/**
- * Tests.
- */
-testing.describe(guardType.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardType).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          guardType(TESTING_STRING, 'string', (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-          guardType(TESTING_NUMBER, 'number', (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_NUMBER);
-            }
-            return result;
-          });
-        })
-        // ... instance.
-        .describe(`instance`, () => testing.it(`Class`, () => expect(guardType<TestingClass>(TESTING_CLASS, TestingClass)).toBeTrue()))
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`${TESTING_FUNCTION}`, () => expect(guardType(TESTING_FUNCTION, 'function')).toBeTrue())
-            .it(`${TESTING_CLASS}`, () => expect(guardType(TestingClass, 'function')).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`CLASS`, () => expect(guardType(TESTING_CLASS, 'object')).toBeTrue())
-            .it(`TESTING_OBJECT`, () => expect(guardType(TESTING_OBJECT, 'object')).toBeTrue());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(guardType(TESTING_BIGINT, 'bigint')).toBeTrue()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(guardType(TESTING_TRUE, 'boolean')).toBeTrue())
-                .it(`${TESTING_FALSE}`, () => expect(guardType(TESTING_FALSE, 'boolean')).toBeTrue());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(guardType(TESTING_NULL, 'null')).toBeTrue())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(guardType(TESTING_NUMBER, 'number')).toBeTrue())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(guardType(TESTING_NUMBER_CONSTRUCTOR, 'number')).toBeTrue());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(guardType(TESTING_STRING, 'string')).toBeTrue())
-                .it(`String(${TESTING_STRING})`, () => expect(guardType(TESTING_STRING_CONSTRUCTOR, 'string')).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(guardType(TESTING_SYMBOL_NUMBER, 'symbol')).toBeTrue())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(guardType(TESTING_SYMBOL_STRING, 'symbol')).toBeTrue());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(guardType(TESTING_UNDEFINED, 'undefined')).toBeTrue())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(guardType(TESTING_BIGINT, 'bigint')).toBeTrue()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(guardType(TESTING_TRUE_INSTANCE, 'boolean')).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(guardType(TESTING_FALSE_INSTANCE, 'boolean')).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(guardType(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(guardType(TESTING_STRING_INSTANCE, 'string')).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/guard/test/guard-undefined.spec.ts b/src/guard/test/guard-undefined.spec.ts
deleted file mode 100644
index a8efc6b5..00000000
--- a/src/guard/test/guard-undefined.spec.ts
+++ /dev/null
@@ -1,50 +0,0 @@
-// Function.
-import { guardUndefined } from '../lib/guard-undefined.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_UNDEFINED,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.guard.undefined.describe,
-  tests.guard.undefined.it
-);
-/**
- * Tests.
- */
-testing.describe(guardUndefined.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(guardUndefined).toBeDefined())
-
-    // Checks ...
-    .describe(`guards`, () => {
-      testing
-        .it('with callback and payload', () => {
-          guardUndefined(TESTING_UNDEFINED, (result, value, payload) => {
-            expect(result).toBeTrue();
-            expect(value).toEqual(TESTING_UNDEFINED);
-            if (payload) {
-              expect(payload.action).toEqual('action');
-              expect(payload.name).toEqual('name');
-              expect(payload.param).toEqual('param');
-            }
-            return result;
-          }, { action: 'action', name: 'name', param: 'param' });
-        })
-        // ... primitives.
-        .describe(`primitive`, () =>
-          testing.it(`${TESTING_UNDEFINED}`, () =>
-            expect(guardUndefined(TESTING_UNDEFINED)).toBeTrue()
-          )
-        );
-    });
-});
diff --git a/src/guard/test/guard.spec.ts b/src/guard/test/guard.spec.ts
deleted file mode 100644
index 52af2893..00000000
--- a/src/guard/test/guard.spec.ts
+++ /dev/null
@@ -1,51 +0,0 @@
-import { guard } from '../lib/guard.object';
-// Testing.
-import {
-   // Main.
-   Testing,
- } from '@angular-package/testing';
- // Execute tests.
-import { tests } from '../../execute-tests';
- /**
-  * Initialize testing.
-  */
-const testing = new Testing(
-   tests.object.guard.describe,
-   tests.object.guard.it
- );
- /**
-  * Tests.
-  */
-testing.describe(`guard`, () => {
-  testing
-  .describe('DEFINED', () => {
-    testing
-    .it('guard', () => expect(guard).toBeDefined())
-    .it('guard.array()', () => expect(guard.array).toBeDefined())
-    .it('guard.bigint()', () => expect(guard.bigint).toBeDefined())
-    .it('guard.boolean()', () => expect(guard.boolean).toBeDefined())
-    .it('guard.class()', () => expect(guard.class).toBeDefined())
-    .it('guard.defined()', () => expect(guard.defined).toBeDefined())
-    .it('guard.false()', () => expect(guard.false).toBeDefined())
-    .it('guard.function()', () => expect(guard.function).toBeDefined())
-    .it('guard.instance()', () => expect(guard.instance).toBeDefined())
-    .it('guard.key()', () => expect(guard.key).toBeDefined())
-    .it('guard.null()', () => expect(guard.null).toBeDefined())
-    .it('guard.number()', () => expect(guard.number).toBeDefined())
-    .it('guard.numberBetween()', () => expect(guard.numberBetween).toBeDefined())
-    .it('guard.object()', () => expect(guard.object).toBeDefined())
-    .it('guard.objectKey()', () => expect(guard.objectKey).toBeDefined())
-    .it('guard.objectKeyIn()', () => expect(guard.objectKeyIn).toBeDefined())
-    .it('guard.objectKeys()', () => expect(guard.objectKeys).toBeDefined())
-    .it('guard.objectKeysIn()', () => expect(guard.objectKeysIn).toBeDefined())
-    .it('guard.objectSomeKeys()', () => expect(guard.objectSomeKeys).toBeDefined())
-    .it('guard.primitive()', () => expect(guard.primitive).toBeDefined())
-    .it('guard.string()', () => expect(guard.string).toBeDefined())
-    .it('guard.stringIncludes()', () => expect(guard.stringIncludes).toBeDefined())
-    .it('guard.stringIncludesSome()', () => expect(guard.stringIncludesSome).toBeDefined())
-    .it('guard.symbol()', () => expect(guard.symbol).toBeDefined())
-    .it('guard.true()', () => expect(guard.true).toBeDefined())
-    .it('guard.type()', () => expect(guard.type).toBeDefined())
-    .it('guard.undefined()', () => expect(guard.undefined).toBeDefined());
-  });
-});
diff --git a/src/interface/index.ts b/src/interface/index.ts
deleted file mode 100644
index 19fd851f..00000000
--- a/src/interface/index.ts
+++ /dev/null
@@ -1 +0,0 @@
-export { MinMax } from './min-max.interface';
diff --git a/src/interface/min-max.interface.ts b/src/interface/min-max.interface.ts
deleted file mode 100644
index 4e0b2098..00000000
--- a/src/interface/min-max.interface.ts
+++ /dev/null
@@ -1,14 +0,0 @@
-/**
- * A generic type `MinMax` that takes generic type variables `Min` and `Max` represents the range between minimum and maximum.
- */
-export interface MinMax<Min extends number, Max extends number> {
-  /**
-   * The minimum value of a generic type variable `Min` constrained by a `number` type.
-   */
-  min?: Min;
-
-  /**
-   * The maximum value of a generic type variable `Max` constrained by a `number` type.
-   */
-  max?: Max;
-}
diff --git a/src/is/index.ts b/src/is/index.ts
deleted file mode 100644
index bbbfdcfc..00000000
--- a/src/is/index.ts
+++ /dev/null
@@ -1,52 +0,0 @@
-// `is` functions.
-export { isArray } from './lib/is-array.func';
-export { isBigInt } from './lib/is-big-int.func';
-export { isBoolean } from './lib/is-boolean.func';
-export { isBooleanObject } from './lib/is-boolean-object.func';
-export { isBooleanType } from './lib/is-boolean-type.func';
-export { isClass } from './lib/is-class.func';
-export { isDate } from './lib/is-date.func'; // From 4.2.0
-export { isDefined } from './lib/is-defined.func';
-export { isFalse } from './lib/is-false.func'; // From 4.2.0
-export { isFunction } from './lib/is-function.func';
-export { isInstance } from './lib/is-instance.func';
-export { isKey } from './lib/is-key.func';
-export { isNull } from './lib/is-null.func';
-export { isNumber } from './lib/is-number.func';
-export { isNumberBetween } from './lib/is-number-between.func'; // From 4.2.0
-export { isNumberObject } from './lib/is-number-object.func';
-export { isNumberType } from './lib/is-number-type.func';
-export { isObject } from './lib/is-object.func';
-export { isObjectKey } from './lib/is-object-key.func';
-export { isObjectKeyIn } from './lib/is-object-key-in.func';
-export { isObjectKeys } from './lib/is-object-keys.func';
-export { isObjectKeysIn } from './lib/is-object-keys-in.func';
-export { isObjectSomeKeys } from './lib/is-object-some-keys.func';
-export { isParam } from './lib/is-param.decorator';
-export { isPrimitive } from './lib/is-primitive.func';
-export { isRegExp } from './lib/is-regexp.func'; // From 4.2.0
-export { isString } from './lib/is-string.func';
-export { isStringIncludes } from './lib/is-string-includes.func';
-export { isStringIncludesSome } from './lib/is-string-includes-some.func';
-export { isStringLength } from './lib/is-string-length.func'; // From 4.2.0
-export { isStringLengthBetween } from './lib/is-string-length-between.func'; // From 5.0.0
-export { isStringObject } from './lib/is-string-object.func';
-export { isStringType } from './lib/is-string-type.func';
-export { isSymbol } from './lib/is-symbol.func';
-export { isTrue } from './lib/is-true.func'; // From 4.2.0
-export { isType } from './lib/is-type.func';
-export { isUndefined } from './lib/is-undefined.func';
-// `is` object.
-export { is } from './lib/is.object';
-// All `isNot` functions.
-export {
-  isNotBoolean,
-  isNotDefined,
-  isNotFunction,
-  isNotNull,
-  isNotNumber,
-  isNotString,
-  isNotUndefined
-} from './not';
-// `isNot`.
-export { isNot } from './not';
diff --git a/src/is/interface/is.interface.ts b/src/is/interface/is.interface.ts
deleted file mode 100644
index 3cc7815a..00000000
--- a/src/is/interface/is.interface.ts
+++ /dev/null
@@ -1,246 +0,0 @@
-// Function.
-import { isArray } from '../lib/is-array.func';
-import { isBigInt } from '../lib/is-big-int.func';
-import { isBoolean } from '../lib/is-boolean.func';
-import { isBooleanObject } from '../lib/is-boolean-object.func';
-import { isBooleanType } from '../lib/is-boolean-type.func';
-import { isClass } from '../lib/is-class.func';
-import { isDate } from '../lib/is-date.func';
-import { isDefined } from '../lib/is-defined.func';
-import { isFalse } from '../lib/is-false.func';
-import { isFunction } from '../lib/is-function.func';
-import { isInstance } from '../lib/is-instance.func';
-import { isKey } from '../lib/is-key.func';
-import { isNull } from '../lib/is-null.func';
-import { isNumber } from '../lib/is-number.func';
-import { isNumberBetween } from '../lib/is-number-between.func';
-import { isNumberObject } from '../lib/is-number-object.func';
-import { isNumberType } from '../lib/is-number-type.func';
-import { isObject } from '../lib/is-object.func';
-import { isObjectKey } from '../lib/is-object-key.func';
-import { isObjectKeyIn } from '../lib/is-object-key-in.func';
-import { isObjectKeys } from '../lib/is-object-keys.func';
-import { isObjectKeysIn } from '../lib/is-object-keys-in.func';
-import { isObjectSomeKeys } from '../lib/is-object-some-keys.func';
-import { isPrimitive } from '../lib/is-primitive.func';
-import { isRegExp } from '../lib/is-regexp.func';
-import { isString } from '../lib/is-string.func';
-import { isStringIncludes } from '../lib/is-string-includes.func';
-import { isStringIncludesSome } from '../lib/is-string-includes-some.func';
-import { isStringLength } from '../lib/is-string-length.func';
-import { isStringLengthBetween } from '../lib/is-string-length-between.func';
-import { isStringObject } from '../lib/is-string-object.func';
-import { isStringType } from '../lib/is-string-type.func';
-import { isSymbol } from '../lib/is-symbol.func';
-import { isTrue } from '../lib/is-true.func';
-import { isType } from '../lib/is-type.func';
-import { isUndefined } from '../lib/is-undefined.func';
-// Type.
-import { IsNot } from '../not/interface/is-not.interface';
-/**
- * Export: Interface.
- * Object with prefixed `is` functions.
- */
-export interface Is {
-  /**
-   * Checks if any value is of the type obtained from its object class equal to `'array'` or an `object` type and passes the test of
-   * `Array.isArray()` method.
-   */
-  array: typeof isArray;
-
-  /**
-   * Checks if any value is a `bigint` type.
-   */
-  bigint: typeof isBigInt;
-
-  /**
-   * Checks if any value is a `boolean` type, or the obtained type from its object class equal to `'boolean'`, or an `object` type and an
-   * instance of `Boolean` that is equal to `true` or `false`.
-   */
-  boolean: typeof isBoolean;
-
-  /**
-   * Checks if any value is of the type obtained from its object class equal to `'boolean'` or an `object` type, and an instance of
-   * `Boolean` and equal `true` or `false`.
-   */
-  booleanObject: typeof isBooleanObject;
-
-  /**
-   * Checks if any value is a `boolean` type equal to `true` or `false`.
-   */
-  booleanType: typeof isBooleanType;
-
-  /**
-   * Checks if any value is a `function` type or the type obtained from its object class equal to `'function'` and an instance of
-   * `Function`.
-   */
-  class: typeof isClass;
-
-  /**
-   * Checks if any value is of the type obtained from its object class equal to `'date'` or an `object` type, and an instance of
-   * `Date`.
-   */
-  date: typeof isDate; // From 4.2.0
-
-  /**
-   * Checks if any value is not an `undefined` type and is not equal to `undefined`.
-   */
-  defined: typeof isDefined;
-
-  /**
-   * Checks if any value is a `boolean` type or an instance of `Boolean` by using `isBoolean()` function, that is equal to `false`.
-   */
-  false: typeof isFalse; // From `4.2.0`
-
-  /**
-   * Checks if any value is a `function` type or the type obtained from its object class equal to `'function'` and an instance of
-   * `Function`.
-   */
-  function: typeof isFunction;
-
-  /**
-   * Checks if any value is an instance of a given `constructor`.
-   */
-  instance: typeof isInstance;
-
-  /**
-   * Checks if any value is one of the `string`, `number`, or `symbol` type.
-   */
-  key: typeof isKey;
-
-  /**
-   * Property of an object consists of `isNot` prefixed functions.
-   */
-  not: IsNot;
-
-  /**
-   * Checks if any value is of the type obtained from its object class equal to `'null'` or an `object` type that is equal to `null`.
-   */
-  null: typeof isNull;
-
-  /**
-   * Checks if any value is a `number` type, or the type obtained from its `Object.prototype` equal to `'number'` or an `object` type
-   * and an instance of `Number`.
-   */
-  number: typeof isNumber;
-
-  /**
-   * Checks if any value is a `number` type or an instance of `Number` by using `isNumber()` between a specified range.
-   */
-  numberBetween: typeof isNumberBetween; // From `4.2.0`
-
-  /**
-   * Checks if any value is of the type obtained from its object class equal to `'number'`, or an `object` type and an instance of `Number`
-   * and **finite** by using the `Number.isFinite()` method and is **valid** by using the `Number.isNaN()` method.
-   */
-  numberObject: typeof isNumberObject;
-
-  /**
-   * Checks if any value is a `number` type and finite by using the `Number.isFinite()` method and valid by the `Number.isNaN()` method.
-   */
-  numberType: typeof isNumberType;
-
-  /**
-   * Checks if any value is an `object` type or the type obtained from its `Object.prototype` equal to `'object'`, and an instance of
-   * `Object`.
-   */
-  object: typeof isObject;
-
-  /**
-   * Checks if any value is an `object` by using the `isObject()` function with its key of the `PropertyKey` type.
-   */
-  objectKey: typeof isObjectKey;
-
-  /**
-   * Checks if any value is an `object` by using the `isObject()` function with a key of the `PropertyKey` in it(or its prototype chain) by
-   * using the `in` operator.
-   */
-  objectKeyIn: typeof isObjectKeyIn;
-
-  /**
-   * Checks if any value is an `object`(by using the `isObject()`) with its keys by using `hasOwnProperty()` method of `Object`.
-   */
-  objectKeys: typeof isObjectKeys;
-
-  /**
-   * Checks if any value is an `object` by using the `isObject()` function with keys of the `PropertyKey` in it(or its prototype chain) by
-   * using the `in` operator.
-   */
-  objectKeysIn: typeof isObjectKeysIn;
-
-  /**
-   * Checks if any value is an `object` by using the `isObject()` function with some of its keys or some groups of its keys of the
-   * `PropertyKey` type.
-   */
-  objectSomeKeys: typeof isObjectSomeKeys;
-
-  /**
-   * Checks if any value is of the generic type `Primitive` or specific type from a given `type` of the generic type `Primitives`.
-   */
-  primitive: typeof isPrimitive;
-
-  /**
-   * Checks if any value is a regular expression of the type obtained from its object class equal to `'regexp'`, or an `object` type,
-   * and an instance of `RegExp`.
-   */
-  regexp: typeof isRegExp; // From 4.2.0
-
-  /**
-   * Checks if any value is a `string` type by using the `isStringType()` function or an instance of `String` by using the
-   * `isStringObject()` function.
-   */
-  string: typeof isString;
-
-  /**
-   * Checks if any `value` is a `string` type and it's not an instance of `Object` and `String` or it's an `object` type, and an instance
-   * of `String` and `Object` that includes all of the specified words.
-   */
-  stringIncludes: typeof isStringIncludes;
-
-  /**
-   * Checks if any value is a `string` type or an instance of `String` by using `isString()` that includes some of the specified
-   * words/sentences.
-   */
-  stringIncludesSome: typeof isStringIncludesSome;
-
-  /**
-   * Checks if any value is a `string` type or an instance of `String`(by using `isString()`) of a specified length.
-   */
-  stringLength: typeof isStringLength;
-
-  /**
-   * Checks if any value is a `string` type or an instance of `String` by using `isString()` of length within the specified range.
-   */
-  stringLengthBetween: typeof isStringLengthBetween;
-
-  /**
-   * Checks if any value is of the type obtained from its `Object.prototype` equal to `'string'` or an `object` type, and an instance of
-   * `String`.
-   */
-  stringObject: typeof isStringObject;
-
-  /**
-   * Checks if any value is a `string` type.
-   */
-  stringType: typeof isStringType;
-
-  /**
-   * Checks if any `value` is a `symbol` type.
-   */
-  symbol: typeof isSymbol;
-
-  /**
-   * Checks if any value is a `boolean` type or an instance of `Boolean`(by using the `isBoolean()`) equal to `true`.
-   */
-  true: typeof isTrue; // From 4.2.0
-
-  /**
-   * Checks if any value is the type from a given `type` of the generic type `Types`.
-   */
-  type: typeof isType;
-
-  /**
-   * Checks if any value is an `undefined` type.
-   */
-  undefined: typeof isUndefined;
-}
diff --git a/src/is/lib/is-array.func.ts b/src/is/lib/is-array.func.ts
deleted file mode 100644
index 58a177ba..00000000
--- a/src/is/lib/is-array.func.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the type obtained from its object class equal to `'array'` or an `object` type and passes the test of
- * `Array.isArray()` method.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `Array`.
- * @angularpackage
- */
-export const isArray = <Type = any, Payload extends object = object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Array<Type> =>
-  callback(
-    (typeOf(value) === 'array' || typeof value === 'object') &&
-      Array.isArray(value),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-big-int.func.ts b/src/is/lib/is-big-int.func.ts
deleted file mode 100644
index 85c70440..00000000
--- a/src/is/lib/is-big-int.func.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `bigint` type.
- * @param value The value of `any` type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `bigint`.
- * @angularpackage
- */
-export const isBigInt = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is bigint => callback(typeof value === 'bigint', value, payload);
diff --git a/src/is/lib/is-boolean-object.func.ts b/src/is/lib/is-boolean-object.func.ts
deleted file mode 100644
index 31bd195a..00000000
--- a/src/is/lib/is-boolean-object.func.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the type obtained from its object class equal to `'boolean'` or an `object` type, and an instance of `Boolean`
- * and equal `true` or `false`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an instance of `Boolean`.
- * @angularpackage
- */
-export const isBooleanObject = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Boolean =>
-  callback(
-    (typeOf(value) === 'boolean' || typeof value === 'object') &&
-    value instanceof Boolean &&
-    (value.valueOf() === true || value.valueOf() === false),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-boolean-type.func.ts b/src/is/lib/is-boolean-type.func.ts
deleted file mode 100644
index 1fba7cd2..00000000
--- a/src/is/lib/is-boolean-type.func.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `boolean` type equal to `true` or `false`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `boolean` type.
- * @angularpackage
- */
-export const isBooleanType = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is boolean =>
-  callback(
-    typeof value === 'boolean' && (value === true || value === false),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-boolean.func.ts b/src/is/lib/is-boolean.func.ts
deleted file mode 100644
index f1837734..00000000
--- a/src/is/lib/is-boolean.func.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { AnyBoolean } from '../../type/any-boolean.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `boolean` type, or the obtained type from its object class equal to `'boolean'`, or an `object` type and an
- * instance of `Boolean` that is equal to `true` or `false`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `boolean` type or an instance of `Boolean`.
- * @angularpackage
- */
-export const isBoolean = <
-  Type extends AnyBoolean = boolean,
-  Payload extends object = object
->(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Type =>
-  callback(
-    (typeof value === 'boolean' ||
-    typeOf(value) === 'boolean' ||
-    (typeof value === 'object' && value instanceof Boolean)) &&
-    (value.valueOf() === true || value.valueOf() === false),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-class.func.ts b/src/is/lib/is-class.func.ts
deleted file mode 100644
index b48bf6b1..00000000
--- a/src/is/lib/is-class.func.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `function` type or the type obtained from its object class equal to `'function'` and an instance of
- * `Function`. It also confirms it's a `class` by checking whether the function converted with `Function.prototype.toString()` to string
- * contains the word `class` at the beginning.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `class`.
- * @angularpackage
- */
-export const isClass = <Class = Function, Payload extends object = object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Class =>
-  callback(
-    typeof value === 'function' ||
-    (typeOf(value) === 'function' && value instanceof Function)
-    ? /class/.test(Function.prototype.toString.call(value).slice(0, 5))
-    : false,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-date.func.ts b/src/is/lib/is-date.func.ts
deleted file mode 100644
index 2afa88ee..00000000
--- a/src/is/lib/is-date.func.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-// Function.
-import { typeOf } from '../../lib/type-of.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the type obtained from its object class equal to `'date'` or an `object` type and an instance of `Date`. It
- * confirms it's a valid date with the `isNaN()` function.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a date.
- * @angularpackage
- */
-export const isDate = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Date =>
-  callback(
-    (typeOf(value) === 'date' || typeof value === 'object') &&
-    value instanceof Date === true &&
-    !isNaN(value),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-defined.func.ts b/src/is/lib/is-defined.func.ts
deleted file mode 100644
index 5b9f64aa..00000000
--- a/src/is/lib/is-defined.func.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { Defined } from '../../type/defined.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is not an `undefined` type and is **not** equal to `undefined`.
- * @param value The value of generic type variable `Type` by default of type captured from itself, to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is defined, not `undefined`.
- * @angularpackage
- */
-export const isDefined = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Defined<Type> =>
-  callback(typeof value !== 'undefined' && value !== undefined, value, payload);
diff --git a/src/is/lib/is-false.func.ts b/src/is/lib/is-false.func.ts
deleted file mode 100644
index e94ab413..00000000
--- a/src/is/lib/is-false.func.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-// Function.
-import { isBoolean } from './is-boolean.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `boolean` type or an instance of `Boolean` by using `isBoolean()` function, that is equal to `false`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `boolean` type or an instance of `Boolean` that
- * is equal to `false`.
- * @angularpackage
- */
-export const isFalse = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is false =>
-  callback(
-    isBoolean(value) ? value.valueOf() === false : false,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-function.func.ts b/src/is/lib/is-function.func.ts
deleted file mode 100644
index 59b1022c..00000000
--- a/src/is/lib/is-function.func.ts
+++ /dev/null
@@ -1,31 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `function` type or the type obtained from its object class equal to `'function'` and an instance of `Function`.
- * It also denies it's a `class` by checking whether the function converted with `Function.prototype.ToString()` to the string does not
- * contain the word `class` at the beginning.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a function.
- * @angularpackage
- */
-export const isFunction = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Function =>
-  callback(
-    typeof value === 'function' ||
-      (typeOf(value) === 'function' && (value as any) instanceof Function)
-      ? /class/.test(Function.prototype.toString.call(value).slice(0, 5)) ===
-          false
-      : false,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-instance.func.ts b/src/is/lib/is-instance.func.ts
deleted file mode 100644
index 60be7b0a..00000000
--- a/src/is/lib/is-instance.func.ts
+++ /dev/null
@@ -1,35 +0,0 @@
-// Function.
-import { isObject } from './is-object.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { Constructor } from '../../type/constructor.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an instance of a given `constructor`.
- * @param value The value of any type to be an instance of a given `constructor`.
- * @param constructor A `class` or `function` that specifies the type of constructor.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with `constructor` under `ctor` name and optional properties from
- * the provided `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an instance of a given `constructor`.
- * @angularpackage
- */
-export const isInstance = <Obj, Payload extends object>(
-  value: any,
-  constructor: Constructor<Obj>,
-  callback: ResultCallback<
-    any,
-    { ctor: typeof constructor } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(
-    isObject(value) &&
-      typeof constructor === 'function' &&
-      constructor instanceof Function
-      ? value instanceof constructor
-      : false,
-    value,
-    { ...payload, ctor: constructor } as any
-  );
diff --git a/src/is/lib/is-key.func.ts b/src/is/lib/is-key.func.ts
deleted file mode 100644
index 0d8caaed..00000000
--- a/src/is/lib/is-key.func.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// Function.
-import { isNumberType } from './is-number-type.func';
-import { isStringType } from './is-string-type.func';
-import { isSymbol } from './is-symbol.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is one of the `string`, `number`, or `symbol` type.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `PropertyKey`.
- * @angularpackage
- */
-export const isKey = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is PropertyKey =>
-  callback(
-    isStringType(value) || isNumberType(value) || isSymbol(value),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-null.func.ts b/src/is/lib/is-null.func.ts
deleted file mode 100644
index bdc7832d..00000000
--- a/src/is/lib/is-null.func.ts
+++ /dev/null
@@ -1,25 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the type obtained from its object class equal to `'null'` or an `object` type that is equal to `null`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is `null`.
- * @angularpackage
- */
-export const isNull = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is null =>
-  callback(
-    (typeOf(value) === 'null' || typeof value === 'object') && value === null,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-number-between.func.ts b/src/is/lib/is-number-between.func.ts
deleted file mode 100644
index fe96921c..00000000
--- a/src/is/lib/is-number-between.func.ts
+++ /dev/null
@@ -1,44 +0,0 @@
-// Function.
-import { isNumber } from './is-number.func';
-import { isNumberType } from './is-number-type.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyNumber } from '../../type/any-number.type';
-import { NumberBetween } from '../../type/number-between.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `number` type or an instance of `Number`(by using `isNumber()`) between a specified range.
- * @param value The value of any type to check.
- * @param min The **minimum** range of generic type variable `Min` for a given `value`.
- * @param max The **maximum** range of generic type variable `Max` for a given `value`.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the minimum and maximum `range` and optional properties from the
- * provided `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a finite number of a `number` type or an instance
- * of `Number` between a specified range.
- * @angularpackage
- */
-export const isNumberBetween = <
-  Type extends AnyNumber = number,
-  Min extends number = number,
-  Max extends number = number,
-  Payload extends object = object
->(
-  value: any,
-  min: Min,
-  max: Max,
-  callback: ResultCallback<
-    any,
-    { min: Min; max: Max } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is NumberBetween<Min, Max, Type> =>
-  callback(
-    isNumber(value)
-      ? (isNumberType(min) ? value.valueOf() >= min : false) &&
-          (isNumberType(max) ? value.valueOf() <= max : false)
-      : false,
-    value,
-    { ...payload, min, max } as any
-  );
diff --git a/src/is/lib/is-number-object.func.ts b/src/is/lib/is-number-object.func.ts
deleted file mode 100644
index bb03213c..00000000
--- a/src/is/lib/is-number-object.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the type obtained from its object class equal to `'number'`, or an `object` type and an instance of `Number`
- * and **finite** by using the `Number.isFinite()` method and is **valid** by using the `Number.isNaN()` method.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an instance of `Number`.
- * @angularpackage
- */
-export const isNumberObject = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Number =>
-  callback(
-    (typeOf(value) === 'number' || typeof value === 'object') &&
-      value instanceof Number &&
-      !Number.isNaN(value.valueOf()) &&
-      Number.isFinite(value.valueOf()),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-number-type.func.ts b/src/is/lib/is-number-type.func.ts
deleted file mode 100644
index 108489f2..00000000
--- a/src/is/lib/is-number-type.func.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `number` type and finite by using the `Number.isFinite()` method and valid by the `Number.isNaN()` method.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `number` type.
- * @angularpackage
- */
-export const isNumberType = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is number =>
-  callback(
-    typeof value === 'number' && Number.isFinite(value) && !Number.isNaN(value),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-number.func.ts b/src/is/lib/is-number.func.ts
deleted file mode 100644
index 3e356e51..00000000
--- a/src/is/lib/is-number.func.ts
+++ /dev/null
@@ -1,36 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { AnyNumber } from '../../type/any-number.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `number` type, or the type obtained from its object class equal to `'number'` or an `object` type
- * and an instance of `Number`. The value is also checked by the `Number.isFinite()` method to determine whether it's finite and is
- * validated by the `Number.isNaN()` method.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a finite number of a `number` type or an instance of
- * `Number`.
- * @angularpackage
- */
-export const isNumber = <
-  Type extends AnyNumber = number,
-  Payload extends object = object
->(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Type =>
-  callback(
-    (typeof value === 'number' ||
-      ((typeOf(value) === 'number' || typeof value === 'object') &&
-        value instanceof Number)) &&
-      !Number.isNaN(value.valueOf()) &&
-      Number.isFinite(value.valueOf()),
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-object-key-in.func.ts b/src/is/lib/is-object-key-in.func.ts
deleted file mode 100644
index 95df8eb6..00000000
--- a/src/is/lib/is-object-key-in.func.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-// Function.
-import { isObject } from './is-object.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `object`(by using the `isObject()`) with a key of the `PropertyKey` in it(or its prototype chain) by
- * using the `in` operator.
- * @param value The value of any type to check against an `object` that contains(or its prototype chain) key from a given `key`.
- * @param key A property key to check if a given `value` contains(or its prototype chain).
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the provided `key` and optional properties from the provided `payload`,
- * to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` that contains(or its prototype chain) a
- * given `key`.
- * @angularpackage
- */
-export const isObjectKeyIn = <Obj = object, Payload extends object = object>(
-  value: any,
-  key: PropertyKey,
-  callback: ResultCallback<any, { key: typeof key } & Payload> = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(isObject(value) ? key in value : false, value, {
-    ...payload,
-    key,
-  } as any);
diff --git a/src/is/lib/is-object-key.func.ts b/src/is/lib/is-object-key.func.ts
deleted file mode 100644
index de372df4..00000000
--- a/src/is/lib/is-object-key.func.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-// Function.
-import { isObject } from './is-object.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `object`(by using the `isObject()`) with its key of the `PropertyKey` type.
- * @param value The value of any type to check against an `object` that contains a key from a given `key`.
- * @param key A property key to check if a given `value` contains.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the provided `key` and optional properties from the provided
- * `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` with its `key`.
- * @angularpackage
- */
-export const isObjectKey = <
-  Obj extends object,
-  Payload extends object = object
->(
-  value: any,
-  key: PropertyKey,
-  callback: ResultCallback<any, { key: typeof key } & Payload> = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(
-    isObject(value) ? {}.hasOwnProperty.call(value, key) : false,
-    value,
-    { ...payload, key } as any
-  );
diff --git a/src/is/lib/is-object-keys-in.func.ts b/src/is/lib/is-object-keys-in.func.ts
deleted file mode 100644
index c6090c35..00000000
--- a/src/is/lib/is-object-keys-in.func.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-// Function.
-import { isArray } from './is-array.func';
-import { isObject } from './is-object.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `object`(by using the `isObject()`) with keys of the `PropertyKey` in it(or its prototype chain) by using the
- * `in` operator.
- * @param value The value of any type to check against the `object` that contains(or its prototype chain) keys from the given `keys`.
- * @param key An array of property keys to check if the given `value` contains(or its prototype chain).
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the provided `keys` and optional properties from the provided
- * `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` that contains(or its prototype chain)
- * given `keys`.
- * @angularpackage
- */
-export const isObjectKeysIn = <Obj = object, Payload extends object = object>(
-  value: any,
-  keys: PropertyKey[],
-  callback: ResultCallback<
-    any,
-    { keys: typeof keys } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(
-    isObject(value) && isArray(keys) ? keys.every((k) => k in value) : false,
-    value,
-    { ...payload, keys } as any
-  );
diff --git a/src/is/lib/is-object-keys.func.ts b/src/is/lib/is-object-keys.func.ts
deleted file mode 100644
index c35a076b..00000000
--- a/src/is/lib/is-object-keys.func.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-// Function.
-import { isArray } from './is-array.func';
-import { isObject } from './is-object.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `object`(by using the `isObject()`) with its keys by using `hasOwnProperty()` method of `Object`.
- * @param value The value of any type to check against an `object` that contains its keys from given `keys`.
- * @param keys An `Array` of property keys to check if a given `value` contains.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the provided `keys` and optional properties from the provided
- * `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` with its `keys`.
- * @angularpackage
- */
-export const isObjectKeys = <Obj = object, Payload extends object = object>(
-  value: any,
-  keys: PropertyKey[],
-  callback: ResultCallback<
-    any,
-    { keys: typeof keys } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(
-    isObject(value) && isArray(keys)
-      ? keys.every((key) => ({}.hasOwnProperty.call(value, key)))
-      : false,
-    value,
-    { ...payload, keys } as any
-  );
diff --git a/src/is/lib/is-object-some-keys.func.ts b/src/is/lib/is-object-some-keys.func.ts
deleted file mode 100644
index c81bd734..00000000
--- a/src/is/lib/is-object-some-keys.func.ts
+++ /dev/null
@@ -1,45 +0,0 @@
-// Function.
-import { isArray } from './is-array.func';
-import { isObject } from './is-object.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `object`(by using the `isObject()`) with some of its keys or some groups of its keys of the `PropertyKey` type.
- * @param value The value of any type to check against an `object` that contains some of its keys or some groups of its keys from
- * a given `keys`.
- * @param keys An `Array` of property names or a two-dimensional `array` of property names to check if the given `value` contains some of
- * them or some groups of them.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the provided `keys` and optional properties from the provided
- * `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object` with some of its keys or some groups of
- * its keys from a given `keys`.
- * @angularpackage
- */
-export const isObjectSomeKeys = <
-  Obj extends object,
-  Payload extends object = object
->(
-  value: any,
-  keys: (PropertyKey | PropertyKey[])[],
-  callback: ResultCallback<
-    any,
-    { keys: typeof keys } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(
-    isObject(value) && isArray(keys)
-      ? keys.some((someKey) =>
-          isArray(someKey)
-            ? someKey.every((everyKey) =>
-                ({}.hasOwnProperty.call(value, everyKey))
-              )
-            : {}.hasOwnProperty.call(value, someKey) === true
-        )
-      : false,
-    value,
-    { ...payload, keys } as any
-  );
diff --git a/src/is/lib/is-object.func.ts b/src/is/lib/is-object.func.ts
deleted file mode 100644
index 7fd24258..00000000
--- a/src/is/lib/is-object.func.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `object` type or the type obtained from its object class equal to `'object'`, and an instance of
- * `Object`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an `object`.
- * @angularpackage
- */
-export const isObject = <Obj = object, Payload extends object = object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Obj =>
-  callback(
-    (typeof value === 'object' || typeOf(value) === 'object') &&
-      value instanceof Object,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-param.decorator.ts b/src/is/lib/is-param.decorator.ts
deleted file mode 100644
index 63c89d43..00000000
--- a/src/is/lib/is-param.decorator.ts
+++ /dev/null
@@ -1,39 +0,0 @@
-import { is } from './is.object';
-
-export function isParam(...param: Array<string>): MethodDecorator {
-  return (target: Function | object, key: string | symbol, descriptor: any): any => {
-    const originalMethod = descriptor.value;
-
-    descriptor.value =  function(): void {
-      if (is.array(param) && is.defined(arguments)) {
-        param.forEach((name: string, index: number) => {
-          if (is.number(index) && index < arguments.length) {
-            if (is.defined(arguments[index])) {
-              switch (name) {
-                case 'number':
-                  if (is.number(arguments[index]) === false) {
-                    arguments[index] = undefined;
-                  }
-                  break;
-                case 'object':
-                  if (is.object(arguments[index]) === false) {
-                    arguments[index] = undefined;
-                  }
-                  break;
-                case 'string':
-                  if (is.string(arguments[index]) === false) {
-                    arguments[index] = undefined;
-                  }
-                  break;
-              }
-            }
-          }
-        });
-      }
-      const result = originalMethod.apply(this, arguments);
-      return result;
-    };
-
-    return descriptor;
-  };
-}
diff --git a/src/is/lib/is-primitive.func.ts b/src/is/lib/is-primitive.func.ts
deleted file mode 100644
index 760df78e..00000000
--- a/src/is/lib/is-primitive.func.ts
+++ /dev/null
@@ -1,49 +0,0 @@
-// Function.
-import { isBigInt } from './is-big-int.func';
-import { isBooleanType } from './is-boolean-type.func';
-import { isNull } from './is-null.func';
-import { isNumberType } from './is-number-type.func';
-import { isStringType } from './is-string-type.func';
-import { isSymbol } from './is-symbol.func';
-import { isUndefined } from './is-undefined.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { Primitive } from '../../type/primitive.type';
-import { Primitives } from '../../type/primitives.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the generic type `Primitive` or specific type from a given `type` of the generic type `Primitives`.
- * @param value The value` of any type to check.
- * @param type An optional value of `Primitives` type indicates against which type the provided `value` is checked.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the provided `type` of `Primitives` and additional properties from the
- * provided `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a type of the `Primitives`.
- * @angularpackage
- */
-export const isPrimitive = <
-  Type extends Primitive,
-  Payload extends object = object
->(
-  value: any,
-  type?: Primitives,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Type =>
-  isStringType(type)
-    ? {
-        bigint: isBigInt,
-        boolean: isBooleanType,
-        number: isNumberType,
-        null: isNull,
-        string: isStringType,
-        symbol: isSymbol,
-        undefined: isUndefined,
-      }[type](value, callback, payload)
-    : callback(
-        isNull(value) ||
-          (typeof value !== 'object' && typeof value !== 'function'),
-        value,
-        payload
-      );
diff --git a/src/is/lib/is-regexp.func.ts b/src/is/lib/is-regexp.func.ts
deleted file mode 100644
index 0fea66fd..00000000
--- a/src/is/lib/is-regexp.func.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a regular expression of the type obtained from its object class equal to `'regexp'`, or an `object` type,
- * and an instance of `RegExp`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a regular expression.
- * @angularpackage
- */
-export const isRegExp = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is RegExp =>
-  callback(
-    (typeOf(value) === 'regexp' || typeof value === 'object') &&
-      value instanceof RegExp,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-string-includes-some.func.ts b/src/is/lib/is-string-includes-some.func.ts
deleted file mode 100644
index bb91c5dd..00000000
--- a/src/is/lib/is-string-includes-some.func.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-// Function.
-import { isArray } from './is-array.func';
-import { isString } from './is-string.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `string` type or an instance of `String`(by using `isString()`) that includes some of the specified
- * words/sentences.
- * @param value The value of any type to check against the `string` that `includes` some of the words/sentences.
- * @param includes An `Array` of `string` as words/sentences to be case-sensitive searched for within a given `value`.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the `includes` and optional properties from the provided `payload`,
- * to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String` that
- * includes some of the specified words/sentences.
- * @angularpackage
- */
-export const isStringIncludesSome = <
-  Type extends AnyString = string,
-  Payload extends object = object
->(
-  value: any,
-  includes: string[],
-  callback: ResultCallback<
-    any,
-    { includes: typeof includes } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Type =>
-  callback(
-    isString(value)
-      ? isArray(includes)
-        ? includes.some((include) => value.valueOf().includes(include))
-        : false
-      : false,
-    value,
-    { ...payload, includes } as any
-  );
diff --git a/src/is/lib/is-string-includes.func.ts b/src/is/lib/is-string-includes.func.ts
deleted file mode 100644
index 5a1ced60..00000000
--- a/src/is/lib/is-string-includes.func.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-// Function.
-import { isArray } from './is-array.func';
-import { isString } from './is-string.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `string` type or an instance of `String`(by using `isString()`) that includes all of the specified
- * words/sentences.
- * @param value The value of any type to check against the `string` that contains words/sentences from a given `includes`.
- * @param includes An `Array` of `string` as words/sentences to be case-sensitive searched for within the given `value`.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the `includes` and optional properties from the provided `payload`,
- * to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String` that
- * includes all of the specified words/sentences.
- * @angularpackage
- */
-export const isStringIncludes = <
-  Type extends AnyString = string,
-  Payload extends object = object
->(
-  value: any,
-  includes: string[],
-  callback: ResultCallback<
-    any,
-    { includes: typeof includes } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is Type =>
-  callback(
-    isString(value)
-      ? isArray(includes)
-        ? includes.every((include) => value.valueOf().includes(include))
-        : false
-      : false,
-    value,
-    { ...payload, includes } as any
-  );
diff --git a/src/is/lib/is-string-length-between.func.ts b/src/is/lib/is-string-length-between.func.ts
deleted file mode 100644
index 0d2fb31d..00000000
--- a/src/is/lib/is-string-length-between.func.ts
+++ /dev/null
@@ -1,48 +0,0 @@
-// Function.
-import { isNumberType } from './is-number-type.func';
-import { isString } from './is-string.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-import { StringOfLength } from '../../type/string-of-length.type';
-/**
- * Checks if any value is a `string` type or an instance of `String` by using `isString()` of length within the specified range.
- * @param value The value of any type to check.
- * @param min The **minimum** length of generic type variable `Min` of a given `value`.
- * @param max The **maximum** length of generic type variable `Max` of a given `value`.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the minimum and maximum `length` and optional properties from the
- * provided `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String` of length
- * within the specified range.
- * @angularpackage
- */
-export const isStringLengthBetween = <
-  Type extends AnyString = string,
-  Min extends number = number,
-  Max extends number = number,
-  Payload extends object = object
->(
-  value: any,
-  min: Min,
-  max: Max,
-  callback: ResultCallback<
-    any,
-    { min: Min; max: Max } & Payload
-  > = resultCallback,
-  payload?: Payload
-): value is StringOfLength<Min, Max, Type> =>
-  callback(
-    isString(value)
-      ? (isNumberType(min) && min >= 0
-          ? value.valueOf().length >= min
-          : false) &&
-          (isNumberType(max) && max >= 0
-            ? value.valueOf().length <= max
-            : false)
-      : false,
-    value,
-    { ...payload, min, max } as any
-  );
diff --git a/src/is/lib/is-string-length.func.ts b/src/is/lib/is-string-length.func.ts
deleted file mode 100644
index f4f96160..00000000
--- a/src/is/lib/is-string-length.func.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-// Function.
-import { isNumberType } from './is-number-type.func';
-import { isString } from './is-string.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-import { StringOfLength } from '../../type/string-of-length.type';
-/**
- * Checks if any value is a `string` type or an instance of `String`(by using `isString()`) of a specified length.
- * @param value The value of any type to check.
- * @param length The length of generic type variable `Length` of a given `value`.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload`, with the minimum and maximum `length` and optional properties from the
- * provided `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String` of the
- * specified length.
- * @angularpackage
- */
-export const isStringLength = <
-  Type extends AnyString = string,
-  Length extends number = number,
-  Payload extends object = object
->(
-  value: any,
-  length: Length,
-  callback: ResultCallback<any, { length: Length } & Payload> = resultCallback,
-  payload?: Payload
-): value is StringOfLength<Length, Length, Type> =>
-  callback(
-    isString(value) && isNumberType(length) && length > 0
-      ? value.valueOf().length === length
-      : false,
-    value,
-    { ...payload, length } as any
-  );
diff --git a/src/is/lib/is-string-object.func.ts b/src/is/lib/is-string-object.func.ts
deleted file mode 100644
index 7c4bff16..00000000
--- a/src/is/lib/is-string-object.func.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is of the type obtained from its object class equal to `'string'` or an `object` type, and an instance of `String`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is an instance of `String`.
- * @angularpackage
- */
-export const isStringObject = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is String =>
-  callback(
-    (typeOf(value) === 'string' || typeof value === 'object') &&
-    value instanceof String,
-    value,
-    payload
-  );
diff --git a/src/is/lib/is-string-type.func.ts b/src/is/lib/is-string-type.func.ts
deleted file mode 100644
index c62fe353..00000000
--- a/src/is/lib/is-string-type.func.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `string` type.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type.
- * @angularpackage
- */
-export const isStringType = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is string =>
-  callback(typeof value === 'string', value, payload);
diff --git a/src/is/lib/is-string.func.ts b/src/is/lib/is-string.func.ts
deleted file mode 100644
index aab4bd3b..00000000
--- a/src/is/lib/is-string.func.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-import { isStringObject } from './is-string-object.func';
-import { isStringType } from './is-string-type.func';
-// Type.
-import { AnyString } from '../../type/any-string.type';
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `string` type by using the `isStringType()` function or an instance of `String` by using the `isStringObject()`
- * function.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `string` type or an instance of `String`.
- * @angularpackage
- */
-export const isString = <
-  Type extends AnyString = string,
-  Payload extends object = object
->(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is Type =>
-  callback(isStringType(value) || isStringObject(value), value, payload);
diff --git a/src/is/lib/is-symbol.func.ts b/src/is/lib/is-symbol.func.ts
deleted file mode 100644
index 760d514f..00000000
--- a/src/is/lib/is-symbol.func.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `symbol` type.
- * @var Payload The `Payload` generic type variable constrained by `object` indicates the type of optional parameter `payload` of the
- * supplied `callback` function and `payload` optional parameter of the `isSymbol()` function from which it captures its value.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `symbol`.
- * @angularpackage
- */
-export const isSymbol = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is symbol =>
-  callback(typeof value === 'symbol', value, payload);
diff --git a/src/is/lib/is-true.func.ts b/src/is/lib/is-true.func.ts
deleted file mode 100644
index b28161f6..00000000
--- a/src/is/lib/is-true.func.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-// Function.
-import { isBoolean } from './is-boolean.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is a `boolean` type or an instance of `Boolean`(by using the `isBoolean()`) equal to `true`.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a `boolean` type or an instance of `Boolean` that is
- * equal to `true`.
- * @angularpackage
- */
-export const isTrue = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is true =>
-  callback(isBoolean(value) ? value.valueOf() === true : false, value, payload);
diff --git a/src/is/lib/is-type.func.ts b/src/is/lib/is-type.func.ts
deleted file mode 100644
index ee6d01b7..00000000
--- a/src/is/lib/is-type.func.ts
+++ /dev/null
@@ -1,50 +0,0 @@
-// Function.
-import { isBigInt } from './is-big-int.func';
-import { isBooleanType } from './is-boolean-type.func';
-import { isFunction } from './is-function.func';
-import { isInstance } from './is-instance.func';
-import { isNotNull } from '../not/lib/is-not-null.func';
-import { isNull } from './is-null.func';
-import { isNumberType } from './is-number-type.func';
-import { isObject } from './is-object.func';
-import { isStringType } from './is-string-type.func';
-import { isSymbol } from './is-symbol.func';
-import { isUndefined } from './is-undefined.func';
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { Primitives } from '../../type/primitives.type';
-import { ResultCallback } from '../../type/result-callback.type';
-import { Type } from '../../type/type.type';
-import { Types } from '../../type/types.type';
-/**
- * Checks if any value is the type from a given `type` of the generic type `Types`.
- * @param value The value of any type to check against the type of given `type`.
- * @param type A value of the generic type `Types` indicates against which type the provided `value` is checked.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with the provided `type` and optional properties from the provided
- * `payload`, to handle them before the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is a type from a given `type`.
- * @angularpackage
- */
-export const isType = <T extends Type, Payload extends object = object>(
-  value: any,
-  type: Types<T>,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is T =>
-  isStringType(type)
-    ? {
-        bigint: isBigInt,
-        boolean: isBooleanType,
-        function: isFunction,
-        number: isNumberType,
-        object: isObject,
-        null: isNull,
-        string: isStringType,
-        symbol: isSymbol,
-        undefined: isUndefined,
-      }[type as Primitives](value, callback, payload)
-    : isNotNull(type)
-    ? isInstance(value, type, callback, payload)
-    : false;
diff --git a/src/is/lib/is-undefined.func.ts b/src/is/lib/is-undefined.func.ts
deleted file mode 100644
index 57070ac4..00000000
--- a/src/is/lib/is-undefined.func.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-// Function.
-import { resultCallback } from '../../lib/result-callback.func';
-// Type.
-import { ResultCallback } from '../../type/result-callback.type';
-/**
- * Checks if any value is an `undefined` type.
- * @param value The value of any type to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is `undefined`.
- * @angularpackage
- */
-export const isUndefined = <Payload extends object>(
-  value: any,
-  callback: ResultCallback<any, Payload> = resultCallback,
-  payload?: Payload
-): value is undefined => callback(typeof value === 'undefined', value, payload);
diff --git a/src/is/lib/is.object.ts b/src/is/lib/is.object.ts
deleted file mode 100644
index 9f23c52c..00000000
--- a/src/is/lib/is.object.ts
+++ /dev/null
@@ -1,83 +0,0 @@
-// Function.
-import { isArray } from './is-array.func';
-import { isBigInt } from './is-big-int.func';
-import { isBoolean } from './is-boolean.func';
-import { isBooleanObject } from './is-boolean-object.func';
-import { isBooleanType } from './is-boolean-type.func';
-import { isClass } from './is-class.func';
-import { isDate } from './is-date.func';
-import { isDefined } from './is-defined.func';
-import { isFalse } from './is-false.func';
-import { isFunction } from './is-function.func';
-import { isInstance } from './is-instance.func';
-import { isKey } from './is-key.func';
-import { isNull } from './is-null.func';
-import { isNumber } from './is-number.func';
-import { isNumberBetween } from './is-number-between.func';
-import { isNumberObject } from './is-number-object.func';
-import { isNumberType } from './is-number-type.func';
-import { isObject } from './is-object.func';
-import { isObjectKey } from './is-object-key.func';
-import { isObjectKeyIn } from './is-object-key-in.func';
-import { isObjectKeys } from './is-object-keys.func';
-import { isObjectKeysIn } from './is-object-keys-in.func';
-import { isObjectSomeKeys } from './is-object-some-keys.func';
-import { isPrimitive } from './is-primitive.func';
-import { isRegExp } from './is-regexp.func';
-import { isString } from './is-string.func';
-import { isStringIncludes } from './is-string-includes.func';
-import { isStringIncludesSome } from './is-string-includes-some.func';
-import { isStringLength } from './is-string-length.func';
-import { isStringLengthBetween } from './is-string-length-between.func';
-import { isStringObject } from './is-string-object.func';
-import { isStringType } from './is-string-type.func';
-import { isSymbol } from './is-symbol.func';
-import { isTrue } from './is-true.func';
-import { isType } from './is-type.func';
-import { isUndefined } from './is-undefined.func';
-// Object.
-import { isNot } from '../not/lib/is-not.object';
-// Interface.
-import { Is } from '../interface/is.interface';
-/**
- * The object contains prefixed with is functions and prefixed with isNot functions in property `not`.
- */
-export const is: Is = Object.freeze({
-  array: isArray,
-  bigint: isBigInt,
-  boolean: isBoolean,
-  booleanObject: isBooleanObject,
-  booleanType: isBooleanType,
-  class: isClass,
-  date: isDate, // From the `4.2.0` version.
-  defined: isDefined,
-  false: isFalse, // From the `4.2.0` version.
-  function: isFunction,
-  instance: isInstance,
-  key: isKey,
-  not: isNot,
-  null: isNull,
-  number: isNumber,
-  numberBetween: isNumberBetween, // From the `4.2.0` version.
-  numberObject: isNumberObject,
-  numberType: isNumberType,
-  object: isObject,
-  objectKey: isObjectKey,
-  objectKeyIn: isObjectKeyIn,
-  objectKeys: isObjectKeys,
-  objectKeysIn: isObjectKeysIn, // From the `5.0.0` version.
-  objectSomeKeys: isObjectSomeKeys, // From the `5.0.0` version.
-  primitive: isPrimitive,
-  regexp: isRegExp, // From the `4.2.0` version.
-  string: isString,
-  stringIncludes: isStringIncludes, // From the `5.0.0` version.
-  stringIncludesSome: isStringIncludesSome, // From the `5.0.0` version.
-  stringLength: isStringLength, // From the `4.2.0` version.
-  stringLengthBetween: isStringLengthBetween, // From the 5.0.0 version.
-  stringObject: isStringObject,
-  stringType: isStringType,
-  symbol: isSymbol,
-  true: isTrue, // From the `4.2.0` version.
-  type: isType,
-  undefined: isUndefined
-});
diff --git a/src/is/not/index.ts b/src/is/not/index.ts
deleted file mode 100644
index 14c32b52..00000000
--- a/src/is/not/index.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-// Functions.
-export { isNotBoolean } from './lib/is-not-boolean.func';
-export { isNotDefined } from './lib/is-not-defined.func';
-export { isNotFunction } from './lib/is-not-function.func';
-export { isNotNull } from './lib/is-not-null.func';
-export { isNotNumber } from './lib/is-not-number.func';
-export { isNotString } from './lib/is-not-string.func';
-export { isNotUndefined } from './lib/is-not-undefined.func';
-// Object.
-export { isNot } from './lib/is-not.object';
diff --git a/src/is/not/interface/is-not.interface.ts b/src/is/not/interface/is-not.interface.ts
deleted file mode 100644
index 1c1afe05..00000000
--- a/src/is/not/interface/is-not.interface.ts
+++ /dev/null
@@ -1,26 +0,0 @@
-// Function.
-import { isNotBoolean } from '../lib/is-not-boolean.func';
-import { isNotDefined } from '../lib/is-not-defined.func';
-import { isNotFunction } from '../lib/is-not-function.func';
-import { isNotNull } from '../lib/is-not-null.func';
-import { isNotNumber } from '../lib/is-not-number.func';
-import { isNotString } from '../lib/is-not-string.func';
-import { isNotUndefined } from '../lib/is-not-undefined.func';
-/**
- * A shape of an object with all prefixed with `isNot` functions.
- */
-export interface IsNot {
-  // array: IsArray;
-  // bigInt: IsBigInt;
-  boolean: typeof isNotBoolean;
-  defined: typeof isNotDefined;
-  function: typeof isNotFunction;
-  null: typeof isNotNull;
-  number: typeof isNotNumber;
-  // object: IsObject;
-  // primitive: IsPrimitive;
-  string: typeof isNotString;
-  // symbol: IsSymbol;
-  // type: IsType;
-  undefined: typeof isNotUndefined;
-}
diff --git a/src/is/not/lib/is-not-boolean.func.ts b/src/is/not/lib/is-not-boolean.func.ts
deleted file mode 100644
index 30cbe902..00000000
--- a/src/is/not/lib/is-not-boolean.func.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { AnyBoolean } from '../../../type/any-boolean.type';
-import { Never } from '../../../type/never.type';
-import { ResultCallback } from '../../../type/result-callback.type';
-/**
- * Checks if the `value` is not the type obtained from its object class equal to `'boolean'`, not a `boolean` type and not an instance of
- * `Boolean`.
- * @param value The `value` of generic type variable `Type`, by default of the type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is not `boolean` type and not an instance of `Boolean`.
- * @angularpackage
- */
-export const isNotBoolean = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Never<AnyBoolean, Type> =>
-  callback(
-    typeOf(value) !== 'boolean' &&
-      typeof value !== 'boolean' &&
-      value instanceof Boolean === false,
-    value,
-    payload
-  );
diff --git a/src/is/not/lib/is-not-defined.func.ts b/src/is/not/lib/is-not-defined.func.ts
deleted file mode 100644
index 591a8cbd..00000000
--- a/src/is/not/lib/is-not-defined.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../../type/result-callback.type';
-import { Undefined } from '../../../type/undefined.type';
-/**
- * Checks if the `value` is **not** the type obtained from its object class equal to `'undefined'`, **not** an `undefined` type and is
- * **not** equal to `undefined`.
- * @param value The `value` of a generic type variable `Type`, by default of the type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is not defined.
- * @angularpackage
- */
-export const isNotDefined = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Undefined<Type> =>
-  callback(
-    typeOf(value) === 'undefined' &&
-      typeof value === 'undefined' &&
-      value === undefined,
-    value,
-    payload
-  );
diff --git a/src/is/not/lib/is-not-function.func.ts b/src/is/not/lib/is-not-function.func.ts
deleted file mode 100644
index abac895d..00000000
--- a/src/is/not/lib/is-not-function.func.ts
+++ /dev/null
@@ -1,29 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { Never } from '../../../type/never.type';
-import { ResultCallback } from '../../../type/result-callback.type';
-/**
- * Checks if the `value` is **not** the type obtained from its object class equal to `'function'`, **not** a `function` type and **not** an
- * instance of `Function`.
- * @param value The `value` of a generic type variable `Type`, by default of the type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is not a `function`.
- * @angularpackage
- */
-export const isNotFunction = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Never<Function, Type> =>
-  callback(
-    typeOf(value) !== 'function' &&
-      typeof value !== 'function' &&
-      value instanceof Function === false,
-    value,
-    payload
-  );
diff --git a/src/is/not/lib/is-not-null.func.ts b/src/is/not/lib/is-not-null.func.ts
deleted file mode 100644
index ffb04d6c..00000000
--- a/src/is/not/lib/is-not-null.func.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { ResultCallback } from '../../../type/result-callback.type';
-import { Never } from '../../../type/never.type';
-/**
- * Checks if the `value` is **not** the type obtained from its object class equal to `'null'` and **not** equal to `null`.
- * @param value The `value` of a generic `Type`, by default of type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is not `null`.
- * @angularpackage
- */
-export const isNotNull = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Never<null, Type> =>
-  callback(typeOf(value) !== 'null' && value !== null, value, payload);
diff --git a/src/is/not/lib/is-not-number.func.ts b/src/is/not/lib/is-not-number.func.ts
deleted file mode 100644
index e0969e18..00000000
--- a/src/is/not/lib/is-not-number.func.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { AnyNumber } from '../../../type/any-number.type';
-import { Never } from '../../../type/never.type';
-import { ResultCallback } from '../../../type/result-callback.type';
-/**
- * Checks if the `value` is **not** the type obtained from its object class equal to `'number'`, **not** a `number` type and **not** an
- * instance of `Number`.
- * @param value The `value` of a generic type variable `Type`, by default of the type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is not a `number` type and not an instance of  `Number`.
- * @angularpackage
- */
-export const isNotNumber = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Never<AnyNumber, Type> =>
-  callback(
-    typeOf(value) !== 'number' &&
-      typeof value !== 'number' &&
-      value instanceof Number === false,
-    value,
-    payload
-  );
diff --git a/src/is/not/lib/is-not-string.func.ts b/src/is/not/lib/is-not-string.func.ts
deleted file mode 100644
index 5795986b..00000000
--- a/src/is/not/lib/is-not-string.func.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { AnyString } from '../../../type/any-string.type';
-import { Never } from '../../../type/never.type';
-import { ResultCallback } from '../../../type/result-callback.type';
-/**
- * Checks if the `value` is **not** the type obtained from its object class equal to `'string'`, **not** a `string` type and **not** an
- * instance of `String`.
- * @param value The `value` of a generic type variable `Type`, by default of the type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the provided `value` is not a `string` and not an instance of `String`.
- * @angularpackage
- */
-export const isNotString = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Never<AnyString, Type> =>
-  callback(
-    typeOf(value) !== 'string' &&
-      typeof value !== 'string' &&
-      value instanceof String === false,
-    value,
-    payload
-  );
diff --git a/src/is/not/lib/is-not-undefined.func.ts b/src/is/not/lib/is-not-undefined.func.ts
deleted file mode 100644
index 8d2f004b..00000000
--- a/src/is/not/lib/is-not-undefined.func.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-// Function.
-import { resultCallback } from '../../../lib/result-callback.func';
-import { typeOf } from '../../../lib/type-of.func';
-// Type.
-import { Defined } from '../../../type/defined.type';
-import { ResultCallback } from '../../../type/result-callback.type';
-/**
- * Checks if the `value` is **not** the type obtained from its object class equal to `'undefined'`, **not** an `undefined` type and **not**
- * equal to `undefined`.
- * @param value The `value` of a generic type variable `Type`, by default of the type captured from itself to check.
- * @param callback A callback `function` of `ResultCallback` type with parameters, the `value` that has been checked, the `result` of this
- * check, and `payload` of the generic type variable `Payload` with optional properties from the provided `payload`, to handle them before
- * the `result` return. By default, it uses `resultCallback()` function.
- * @param payload An optional `object` of the generic type variable `Payload` is assigned to the `payload` of the given `callback` function.
- * @returns The return value is a `boolean` indicating whether the `value` is not `undefined`.
- */
-export const isNotUndefined = <Type, Payload extends object = object>(
-  value: Type,
-  callback: ResultCallback<Type, Payload> = resultCallback,
-  payload?: Payload
-): value is Defined<Type> =>
-  callback(
-    typeOf(value) !== 'undefined' &&
-      typeof value !== 'undefined' &&
-      value !== undefined,
-    value,
-    payload
-  );
diff --git a/src/is/not/lib/is-not.object.ts b/src/is/not/lib/is-not.object.ts
deleted file mode 100644
index 4a666029..00000000
--- a/src/is/not/lib/is-not.object.ts
+++ /dev/null
@@ -1,27 +0,0 @@
-// Function.
-import { IsNot } from '../interface/is-not.interface';
-import { isNotBoolean } from './is-not-boolean.func';
-import { isNotDefined } from './is-not-defined.func';
-import { isNotFunction } from './is-not-function.func';
-import { isNotNull } from './is-not-null.func';
-import { isNotNumber } from './is-not-number.func';
-import { isNotString } from './is-not-string.func';
-import { isNotUndefined } from './is-not-undefined.func';
-/**
- * An `object` of `isNot` prefixed functions.
- */
-export const isNot: IsNot = Object.freeze({
-  // TODO array: isArray,
-  // TODO bigInt: isBigInt,
-  boolean: isNotBoolean,
-  defined: isNotDefined,
-  function: isNotFunction,
-  null: isNotNull,
-  number: isNotNumber,
-  // TODO object: isObject,
-  // TODO primitive: isPrimitive,
-  string: isNotString,
-  // TODO symbol: isSymbol,
-  // TODO type: isType,
-  undefined: isNotUndefined
-});
diff --git a/src/is/not/test/is-not-boolean.spec.ts b/src/is/not/test/is-not-boolean.spec.ts
deleted file mode 100644
index 64d477ed..00000000
--- a/src/is/not/test/is-not-boolean.spec.ts
+++ /dev/null
@@ -1,84 +0,0 @@
-// Function.
-import { isNotBoolean } from '../lib/is-not-boolean.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.boolean.describe,
-  tests.is.not.boolean.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotBoolean.name, () => {
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(isNotBoolean).toBeDefined())
-    // FALSE
-    .it(`'bigint'`, () => expect(isNotBoolean(TESTING_BIGINT)).toBeTrue())
-    .it(`Class | CLASS`, () => {
-      expect(isNotBoolean(TestingClass)).toBeTrue();
-      expect(isNotBoolean(TESTING_CLASS)).toBeTrue();
-    })
-    .it(`'function' | Function`, () => expect(isNotBoolean(TESTING_FUNCTION)).toBeTrue())
-    .it(`null | NULL`, () => {
-      expect(isNotBoolean(null)).toBeTrue();
-      expect(isNotBoolean(TESTING_NULL)).toBeTrue();
-    })
-    .it(`'number' | Number`, () => {
-      expect(isNotBoolean(TESTING_NUMBER)).toBeTrue();
-      expect(isNotBoolean(TESTING_NUMBER_CONSTRUCTOR)).toBeTrue();
-      expect(isNotBoolean(TESTING_NUMBER_INSTANCE)).toBeTrue();
-    })
-    .it(`'object' | Object`, () => expect(isNotBoolean(TESTING_OBJECT)).toBeTrue())
-    .it(`'string' | String`, () => {
-      expect(isNotBoolean(TESTING_STRING)).toBeTrue();
-      expect(isNotBoolean(TESTING_STRING_CONSTRUCTOR)).toBeTrue();
-      expect(isNotBoolean(TESTING_STRING_INSTANCE)).toBeTrue();
-    })
-    .it(`'symbol'`, () => {
-      expect(isNotBoolean(TESTING_SYMBOL_NUMBER)).toBeTrue();
-      expect(isNotBoolean(TESTING_SYMBOL_STRING)).toBeTrue();
-    })
-    .it(`'undefined'`, () => expect(isNotBoolean(TESTING_UNDEFINED)).toBeTrue())
-
-    // FALSE
-    .it(`'boolean' | Boolean`, () => {
-      expect(isNotBoolean(TESTING_FALSE)).toBeFalse();
-      expect(isNotBoolean(TESTING_TRUE)).toBeFalse();
-      expect(isNotBoolean(TESTING_FALSE_INSTANCE)).toBeFalse();
-      expect(isNotBoolean(TESTING_TRUE_INSTANCE)).toBeFalse();
-      expect(isNotBoolean(Boolean(false))).toBeFalse();
-      expect(isNotBoolean(Boolean(true))).toBeFalse();
-    });
-});
diff --git a/src/is/not/test/is-not-defined.spec.ts b/src/is/not/test/is-not-defined.spec.ts
deleted file mode 100644
index 7093cce3..00000000
--- a/src/is/not/test/is-not-defined.spec.ts
+++ /dev/null
@@ -1,117 +0,0 @@
-// Function.
-import { isNotDefined } from '../lib/is-not-defined.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.defined.describe,
-  tests.is.not.defined.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotDefined.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isNotDefined).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    .it('callback', () => {
-      isNotDefined(TESTING_STRING, (result: boolean) => {
-        expect(result).toBeFalse();
-        return result;
-      });
-    })
-
-    // ... arrays.
-    .describe(`array`, () => {
-    })
-    // ... function.
-    .describe(`function`, () => {
-      testing
-      .it(`FUNCTION`, () => expect(isNotDefined(TESTING_FUNCTION)).toBeFalse())
-      .it(`Class`, () => expect(isNotDefined(TestingClass)).toBeFalse());
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`CLASS`, () => expect(isNotDefined(TESTING_CLASS)).toBeFalse())
-      .it(`OBJECT_ONE`, () => expect(isNotDefined(TESTING_OBJECT)).toBeFalse());
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => {
-        testing.it(`${TESTING_BIGINT}`, () => expect(isNotDefined(TESTING_BIGINT)).toBeFalse());
-      })
-
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(isNotDefined(TESTING_TRUE)).toBeFalse())
-        .it(`${TESTING_FALSE}`, () => expect(isNotDefined(TESTING_FALSE)).toBeFalse())
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotDefined(TESTING_TRUE_INSTANCE)).toBeFalse())
-        .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNotDefined(TESTING_FALSE_INSTANCE)).toBeFalse());
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(isNotDefined(TESTING_NULL)).toBeFalse())
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(isNotDefined(TESTING_NUMBER)).toBeFalse())
-        .it(`Number(${TESTING_NUMBER})`, () => expect(isNotDefined(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse())
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(isNotDefined(TESTING_NUMBER_INSTANCE)).toBeFalse());
-      })
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(isNotDefined(TESTING_STRING)).toBeFalse())
-        .it(`String(${TESTING_STRING})`, () => expect(isNotDefined(TESTING_STRING_CONSTRUCTOR)).toBeFalse())
-        .it(`new String(${TESTING_STRING})`, () => expect(isNotDefined(TESTING_STRING_INSTANCE)).toBeFalse());
-      })
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNotDefined(TESTING_SYMBOL_NUMBER)).toBeFalse())
-        .it(`Symbol(${TESTING_STRING})`, () => expect(isNotDefined(TESTING_SYMBOL_STRING)).toBeFalse());
-      })
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(isNotDefined(TESTING_UNDEFINED)).toBeTrue());
-    });
-  });
-});
diff --git a/src/is/not/test/is-not-function.spec.ts b/src/is/not/test/is-not-function.spec.ts
deleted file mode 100644
index 30f94f7d..00000000
--- a/src/is/not/test/is-not-function.spec.ts
+++ /dev/null
@@ -1,116 +0,0 @@
-// Function.
-import { isNotFunction } from '../lib/is-not-function.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.function.describe,
-  tests.is.not.function.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotFunction.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isNotFunction).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    .it('callback', () => {
-      isNotFunction(TESTING_STRING, (result: boolean) => {
-        expect(result).toBe(TESTING_TRUE);
-        return result;
-      });
-    })
-    // ... arrays.
-    .describe(`array`, () => { })
-    // ... function.
-    .describe(`function`, () => {
-      testing
-      .it(`FUNCTION`, () => expect(isNotFunction(TESTING_FUNCTION)).toBe(TESTING_FALSE))
-      .it(`Class`, () => expect(isNotFunction(TestingClass)).toBe(TESTING_FALSE));
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`CLASS`, () => expect(isNotFunction(TESTING_CLASS)).toBe(TESTING_TRUE))
-      .it(`OBJECT_ONE`, () => expect(isNotFunction(TESTING_OBJECT)).toBe(TESTING_TRUE));
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => {
-        testing
-        .it(`${TESTING_BIGINT}`, () => expect(isNotFunction(TESTING_BIGINT)).toBe(TESTING_TRUE));
-      })
-
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(isNotFunction(TESTING_TRUE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE}`, () => expect(isNotFunction(TESTING_FALSE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotFunction(TESTING_TRUE_INSTANCE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNotFunction(TESTING_FALSE_INSTANCE)).toBe(TESTING_TRUE));
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(isNotFunction(TESTING_NULL)).toBe(TESTING_TRUE))
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(isNotFunction(TESTING_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Number(${TESTING_NUMBER})`, () => expect(isNotFunction(TESTING_NUMBER_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(isNotFunction(TESTING_NUMBER_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(isNotFunction(TESTING_STRING)).toBe(TESTING_TRUE))
-        .it(`String(${TESTING_STRING})`, () => expect(isNotFunction(TESTING_STRING_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new String(${TESTING_STRING})`, () => expect(isNotFunction(TESTING_STRING_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNotFunction(TESTING_SYMBOL_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Symbol(${TESTING_STRING})`, () => expect(isNotFunction(TESTING_SYMBOL_STRING)).toBe(TESTING_TRUE));
-      })
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(isNotFunction(TESTING_UNDEFINED)).toBe(TESTING_TRUE));
-    });
-  });
-});
diff --git a/src/is/not/test/is-not-null.spec.ts b/src/is/not/test/is-not-null.spec.ts
deleted file mode 100644
index 4d657550..00000000
--- a/src/is/not/test/is-not-null.spec.ts
+++ /dev/null
@@ -1,115 +0,0 @@
-// Function.
-import { isNotNull } from '../lib/is-not-null.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.null.describe,
-  tests.is.not.null.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotNull.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isNotNull).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    .it('callback', () => {
-      isNotNull(TESTING_STRING, (result: boolean) => {
-        expect(result).toBe(TESTING_TRUE);
-        return result;
-      });
-    })
-
-    // ... arrays.
-    .describe(`array`, () => { })
-    // ... function.
-    .describe(`function`, () => {
-      testing
-      .it(`FUNCTION`, () => expect(isNotNull(TESTING_FUNCTION)).toBe(TESTING_TRUE))
-      .it(`Class`, () => expect(isNotNull(TestingClass)).toBe(TESTING_TRUE));
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`CLASS`, () => expect(isNotNull(TESTING_CLASS)).toBe(TESTING_TRUE))
-      .it(`OBJECT_ONE`, () => expect(isNotNull(TESTING_OBJECT)).toBe(TESTING_TRUE));
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => {
-        testing.it(`${TESTING_BIGINT}`, () => expect(isNotNull(TESTING_BIGINT)).toBe(TESTING_TRUE));
-      })
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(isNotNull(TESTING_TRUE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE}`, () => expect(isNotNull(TESTING_FALSE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotNull(TESTING_TRUE_INSTANCE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNotNull(TESTING_FALSE_INSTANCE)).toBe(TESTING_TRUE));
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(isNotNull(TESTING_NULL)).toBe(TESTING_FALSE))
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(isNotNull(TESTING_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Number(${TESTING_NUMBER})`, () => expect(isNotNull(TESTING_NUMBER_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(isNotNull(TESTING_NUMBER_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(isNotNull(TESTING_STRING)).toBe(TESTING_TRUE))
-        .it(`String(${TESTING_STRING})`, () => expect(isNotNull(TESTING_STRING_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new String(${TESTING_STRING})`, () => expect(isNotNull(TESTING_STRING_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNotNull(TESTING_SYMBOL_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Symbol(${TESTING_STRING})`, () => expect(isNotNull(TESTING_SYMBOL_STRING)).toBe(TESTING_TRUE));
-      })
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(isNotNull(TESTING_UNDEFINED)).toBe(TESTING_TRUE));
-    });
-  });
-});
diff --git a/src/is/not/test/is-not-number.spec.ts b/src/is/not/test/is-not-number.spec.ts
deleted file mode 100644
index f0e1883c..00000000
--- a/src/is/not/test/is-not-number.spec.ts
+++ /dev/null
@@ -1,116 +0,0 @@
-// Function.
-import { isNotNumber } from '../lib/is-not-number.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.number.describe,
-  tests.is.not.number.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotNumber.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isNotNumber).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    .it('callback', () => {
-      isNotNumber(TESTING_STRING, (result: boolean) => {
-        expect(result).toBe(TESTING_TRUE);
-        return result;
-      });
-    })
-
-    // ... arrays.
-    .describe(`array`, () => { })
-    // ... function.
-    .describe(`function`, () => {
-      testing
-      .it(`FUNCTION`, () => expect(isNotNumber(TESTING_FUNCTION)).toBe(TESTING_TRUE))
-      .it(`Class`, () => expect(isNotNumber(TestingClass)).toBe(TESTING_TRUE));
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`CLASS`, () => expect(isNotNumber(TESTING_CLASS)).toBe(TESTING_TRUE))
-      .it(`OBJECT_ONE`, () => expect(isNotNumber(TESTING_OBJECT)).toBe(TESTING_TRUE));
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => {
-        testing.it(`${TESTING_BIGINT}`, () => expect(isNotNumber(TESTING_BIGINT)).toBe(TESTING_TRUE));
-      })
-
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(isNotNumber(TESTING_TRUE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE}`, () => expect(isNotNumber(TESTING_FALSE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotNumber(TESTING_TRUE_INSTANCE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNotNumber(TESTING_FALSE_INSTANCE)).toBe(TESTING_TRUE));
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(isNotNumber(TESTING_NULL)).toBe(TESTING_TRUE))
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(isNotNumber(TESTING_NUMBER)).toBe(TESTING_FALSE))
-        .it(`Number(${TESTING_NUMBER})`, () => expect(isNotNumber(TESTING_NUMBER_CONSTRUCTOR)).toBe(TESTING_FALSE))
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(isNotNumber(TESTING_NUMBER_INSTANCE)).toBe(TESTING_FALSE));
-      })
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(isNotNumber(TESTING_STRING)).toBe(TESTING_TRUE))
-        .it(`String(${TESTING_STRING})`, () => expect(isNotNumber(TESTING_STRING_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new String(${TESTING_STRING})`, () => expect(isNotNumber(TESTING_STRING_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNotNumber(TESTING_SYMBOL_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Symbol(${TESTING_STRING})`, () => expect(isNotNumber(TESTING_SYMBOL_STRING)).toBe(TESTING_TRUE));
-      })
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(isNotNumber(TESTING_UNDEFINED)).toBe(TESTING_TRUE));
-    });
-  });
-});
diff --git a/src/is/not/test/is-not-string.spec.ts b/src/is/not/test/is-not-string.spec.ts
deleted file mode 100644
index 6b10897b..00000000
--- a/src/is/not/test/is-not-string.spec.ts
+++ /dev/null
@@ -1,114 +0,0 @@
-// Function.
-import { isNotString } from '../lib/is-not-string.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.string.describe,
-  tests.is.not.string.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotString.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isNotString).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    .it('callback', () => {
-      isNotString(TESTING_STRING, (result: boolean) => {
-        expect(result).toBe(TESTING_FALSE);
-        return result;
-      });
-    })
-
-    // ... arrays.
-    .describe(`array`, () => {})
-    // ... function.
-    .describe(`function`, () => {
-      testing
-      .it(`FUNCTION`, () => expect(isNotString(TESTING_FUNCTION)).toBe(TESTING_TRUE))
-      .it(`Class`, () => expect(isNotString(TestingClass)).toBe(TESTING_TRUE));
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`CLASS`, () => expect(isNotString(TESTING_CLASS)).toBe(TESTING_TRUE))
-      .it(`OBJECT_ONE`, () => expect(isNotString(TESTING_OBJECT)).toBe(TESTING_TRUE));
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => it(`${TESTING_BIGINT}`, () => expect(isNotString(TESTING_BIGINT)).toBe(TESTING_TRUE)))
-
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(isNotString(TESTING_TRUE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE}`, () => expect(isNotString(TESTING_FALSE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotString(TESTING_TRUE_INSTANCE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNotString(TESTING_FALSE_INSTANCE)).toBe(TESTING_TRUE));
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(isNotString(TESTING_NULL)).toBe(TESTING_TRUE))
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(isNotString(TESTING_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Number(${TESTING_NUMBER})`, () => expect(isNotString(TESTING_NUMBER_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(isNotString(TESTING_NUMBER_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(isNotString(TESTING_STRING)).toBe(TESTING_FALSE))
-        .it(`String(${TESTING_STRING})`, () => expect(isNotString(TESTING_STRING_CONSTRUCTOR)).toBe(TESTING_FALSE))
-        .it(`new String(${TESTING_STRING})`, () => expect(isNotString(TESTING_STRING_INSTANCE)).toBe(TESTING_FALSE));
-      })
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNotString(TESTING_SYMBOL_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Symbol(${TESTING_STRING})`, () => expect(isNotString(TESTING_SYMBOL_STRING)).toBe(TESTING_TRUE));
-      })
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(isNotString(TESTING_UNDEFINED)).toBe(TESTING_TRUE));
-    });
-  });
-});
diff --git a/src/is/not/test/is-not-undefined.spec.ts b/src/is/not/test/is-not-undefined.spec.ts
deleted file mode 100644
index 9f312535..00000000
--- a/src/is/not/test/is-not-undefined.spec.ts
+++ /dev/null
@@ -1,115 +0,0 @@
-// Function.
-import { isNotUndefined } from '../lib/is-not-undefined.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.not.undefined.describe,
-  tests.is.not.undefined.it
-);
-/**
- * Tests.
- */
-testing.describe(isNotUndefined.name, () => {
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isNotUndefined).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    .it('callback', () => {
-      isNotUndefined(TESTING_STRING, (result: boolean) => {
-        expect(result).toBe(TESTING_TRUE);
-        return result;
-      });
-    })
-
-    // ... arrays.
-    .describe(`array`, () => {})
-    // ... function.
-    .describe(`function`, () => {
-      testing
-      .it(`FUNCTION`, () => expect(isNotUndefined(TESTING_FUNCTION)).toBe(TESTING_TRUE))
-      .it(`Class`, () => expect(isNotUndefined(TestingClass)).toBe(TESTING_TRUE));
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`CLASS`, () => expect(isNotUndefined(TESTING_CLASS)).toBe(TESTING_TRUE))
-      .it(`OBJECT_ONE`, () => expect(isNotUndefined(TESTING_OBJECT)).toBe(TESTING_TRUE));
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // bigint
-      .describe(`bigint`, () => {
-        testing.it(`${TESTING_BIGINT}`, () => expect(isNotUndefined(TESTING_BIGINT)).toBe(TESTING_TRUE));
-      })
-
-      // boolean
-      .describe(`boolean`, () => {
-        testing
-        .it(`${TESTING_TRUE}`, () => expect(isNotUndefined(TESTING_TRUE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_FALSE}`, () => expect(isNotUndefined(TESTING_FALSE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotUndefined(TESTING_TRUE_INSTANCE)).toBe(TESTING_TRUE))
-        .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNotUndefined(TESTING_TRUE_INSTANCE)).toBe(TESTING_TRUE));
-      })
-
-      // null
-      .it(`${TESTING_NULL}`, () => expect(isNotUndefined(TESTING_NULL)).toBe(TESTING_TRUE))
-
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => expect(isNotUndefined(TESTING_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Number(${TESTING_NUMBER})`, () => expect(isNotUndefined(TESTING_NUMBER_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new Number(${TESTING_NUMBER})`, () => expect(isNotUndefined(TESTING_NUMBER_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => expect(isNotUndefined(TESTING_STRING)).toBe(TESTING_TRUE))
-        .it(`String(${TESTING_STRING})`, () => expect(isNotUndefined(TESTING_STRING_CONSTRUCTOR)).toBe(TESTING_TRUE))
-        .it(`new String(${TESTING_STRING})`, () => expect(isNotUndefined(TESTING_STRING_INSTANCE)).toBe(TESTING_TRUE));
-      })
-      // symbol
-      .describe(`symbol`, () => {
-        testing
-        .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNotUndefined(TESTING_SYMBOL_NUMBER)).toBe(TESTING_TRUE))
-        .it(`Symbol(${TESTING_STRING})`, () => expect(isNotUndefined(TESTING_SYMBOL_STRING)).toBe(TESTING_TRUE));
-      })
-      // undefined
-      .it(`${TESTING_UNDEFINED}`, () => expect(isNotUndefined(TESTING_UNDEFINED)).toBe(TESTING_FALSE));
-    });
-  });
-});
diff --git a/src/is/not/test/is-not.spec.ts b/src/is/not/test/is-not.spec.ts
deleted file mode 100644
index 617ecbc4..00000000
--- a/src/is/not/test/is-not.spec.ts
+++ /dev/null
@@ -1,32 +0,0 @@
-import { isNot } from '../lib/is-not.object';
-// Testing.
-import {
-   // Main.
-   Testing,
- } from '@angular-package/testing';
- // Execute tests.
-import { tests } from '../../../execute-tests';
- /**
-  * Initialize testing.
-  */
-const testing = new Testing(
-   tests.object.isNot.describe,
-   tests.object.isNot.it
- );
- /**
-  * Tests.
-  */
-testing.describe(`guard`, () => {
-   testing
-   .describe('DEFINED', () => {
-      testing
-      .it('isNot', () => expect(isNot).toBeDefined())
-      .it('isNot.boolean()', () => expect(isNot.boolean).toBeDefined())
-      .it('isNot.defined()', () => expect(isNot.defined).toBeDefined())
-      .it('isNot.function()', () => expect(isNot.function).toBeDefined())
-      .it('isNot.null()', () => expect(isNot.null).toBeDefined())
-      .it('isNot.number()', () => expect(isNot.number).toBeDefined())
-      .it('isNot.string()', () => expect(isNot.string).toBeDefined())
-      .it('isNot.undefined()', () => expect(isNot.undefined).toBeDefined());
-   });
-});
diff --git a/src/is/test/is-array.spec.ts b/src/is/test/is-array.spec.ts
deleted file mode 100644
index 89d361ba..00000000
--- a/src/is/test/is-array.spec.ts
+++ /dev/null
@@ -1,110 +0,0 @@
-// Function.
-import { isArray } from '../lib/is-array.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_ARRAY_BIGINT,
-  TESTING_ARRAY_BOOLEAN,
-  TESTING_ARRAY_CLASS,
-  TESTING_ARRAY_FUNCTION,
-  TESTING_ARRAY_NULL,
-  TESTING_ARRAY_NUMBER,
-  TESTING_ARRAY_OBJECT_ONE,
-  TESTING_ARRAY_STRING,
-  TESTING_ARRAY_SYMBOL_NUMBER,
-  TESTING_ARRAY_SYMBOL_STRING,
-  TESTING_ARRAY_UNDEFINED,
-  TESTING_BIGINT,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-
-  // Interface.
-  TestingObject,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.array.describe,
-  tests.is.array.it
-);
-/**
- * Tests.
- */
-testing.describe(isArray.name, () => {
-  let TESTING_NOT_DEFINED: unknown;
-  // TESTING_TRUE
-  testing
-    .it('is DEFINED', () => expect(isArray).toBeDefined())
-    .it(`callback and custom payload`, () => {
-      isArray<bigint, { database: string }>(TESTING_ARRAY_BIGINT, (result, value, payload) => (
-        expect(result).toBeTrue(),
-        expect(value).toEqual(TESTING_ARRAY_BIGINT),
-        expect(payload?.database).toEqual('Person'),
-        result
-      ), { database: 'Person' });
-    })
-    .it('Array<bigint>', () => expect(isArray<bigint>(TESTING_ARRAY_BIGINT)).toBeTrue())
-    .it('Array<boolean>', () => expect(isArray<boolean>(TESTING_ARRAY_BOOLEAN)).toBeTrue())
-    .it('Array<TestingClass>', () => expect(isArray<TestingClass>(TESTING_ARRAY_CLASS)).toBeTrue())
-    .it('Array<Func>', () => expect(isArray<Function>(TESTING_ARRAY_FUNCTION)).toBeTrue())
-    .it('Array<null>', () => expect(isArray<null>(TESTING_ARRAY_NULL)).toBeTrue())
-    .it('Array<number>', () => expect(isArray<number>(TESTING_ARRAY_NUMBER)).toBeTrue())
-    .it('Array<ObjectOne> Array<ObjectTwo>', () => (expect(isArray<TestingObject>(TESTING_ARRAY_OBJECT_ONE)).toBeTrue()))
-    .it('Array<string>', () => expect(isArray<string>(TESTING_ARRAY_STRING)).toBeTrue())
-    .it('Array<symbol>', () => (
-      expect(isArray<symbol>(TESTING_ARRAY_SYMBOL_STRING)).toBeTrue(),
-      expect(isArray<symbol>(TESTING_ARRAY_SYMBOL_NUMBER)).toBeTrue()
-    ))
-    .it('Array<undefined>', () => expect(isArray<undefined>(TESTING_ARRAY_UNDEFINED)).toBeTrue())
-
-    // TESTING_FALSE
-    .it(`'bigint'`, () => expect(isArray(TESTING_BIGINT)).toBeFalse())
-    .it(`'boolean' | Boolean`, () => {
-      expect(isArray(TESTING_FALSE)).toBeFalse();
-      expect(isArray(TESTING_TRUE)).toBeFalse();
-      expect(isArray(TESTING_FALSE_INSTANCE)).toBeFalse();
-      expect(isArray(TESTING_TRUE_INSTANCE)).toBeFalse();
-    })
-    .it(`'function' | Function`, () => expect(isArray(TESTING_FUNCTION)).toBeFalse())
-    .it(`'number' | Number`, () => {
-      expect(isArray(TESTING_NUMBER)).toBeFalse();
-      expect(isArray(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse();
-      expect(isArray(TESTING_NUMBER_INSTANCE)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => {
-      expect(isArray(TESTING_OBJECT)).toBeFalse();
-    })
-    .it(`'string' | String`, () => {
-      expect(isArray(TESTING_STRING)).toBeFalse();
-      expect(isArray(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isArray(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isArray(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => (
-      expect(isArray(TESTING_NOT_DEFINED)).toBeFalse(),
-      expect(isArray(TESTING_UNDEFINED)).toBeFalse()
-    ));
-});
diff --git a/src/is/test/is-big-int.spec.ts b/src/is/test/is-big-int.spec.ts
deleted file mode 100644
index eac70f9c..00000000
--- a/src/is/test/is-big-int.spec.ts
+++ /dev/null
@@ -1,90 +0,0 @@
-// Function.
-import { isBigInt } from '../lib/is-big-int.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.bigint.describe,
-  tests.is.bigint.it
-);
-/**
- * Tests.
- */
-testing.describe(isBigInt.name, () =>
-  testing
-    .toBeInstanceOfFunction(isBigInt)
-    .it(`defined`, () => expect(isBigInt).toBeDefined())
-    .it(`bigint`, () => (
-      expect(isBigInt(TESTING_BIGINT)).toBeTrue(),
-      isBigInt(TESTING_BIGINT, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      }),
-      expect(isBigInt(1n)).toBeTrue()
-    ))
-    .it(`boolean | Boolean`, () => (
-      expect(isBigInt(TESTING_FALSE)).toBeFalse(),
-      expect(isBigInt(TESTING_TRUE)).toBeFalse(),
-      expect(isBigInt(TESTING_FALSE_INSTANCE)).toBeFalse(),
-      expect(isBigInt(TESTING_TRUE_INSTANCE)).toBeFalse(),
-      isBigInt(TESTING_FALSE, (result: boolean) => {
-        expect(result).toBeFalse();
-        return result;
-      })
-    ))
-    .it(`TestingClass | TESTING_CLASS`, () => (
-      expect(isBigInt(TestingClass)).toBeFalse(),
-      expect(isBigInt(TESTING_CLASS)).toBeFalse()
-    ))
-    .it(`function | Function`, () => expect(isBigInt(TESTING_FUNCTION)).toBeFalse())
-    .it(`null | TESTING_NULL`, () => (
-      expect(isBigInt(null)).toBeFalse(),
-      expect(isBigInt(TESTING_NULL)).toBeFalse()
-    ))
-    .it(`'number' | Number`, () => (
-      expect(isBigInt(TESTING_NUMBER)).toBeFalse(),
-      expect(isBigInt(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse(),
-      expect(isBigInt(TESTING_NUMBER_INSTANCE)).toBeFalse()
-    ))
-    .it(`'object' | Object`, () => expect(isBigInt(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => (
-      expect(isBigInt(TESTING_STRING)).toBeFalse(),
-      expect(isBigInt(TESTING_STRING_CONSTRUCTOR)).toBeFalse(),
-      expect(isBigInt(TESTING_STRING_INSTANCE)).toBeFalse()
-    ))
-    .it(`'symbol'`, () => (
-      expect(isBigInt(TESTING_SYMBOL_NUMBER)).toBeFalse(),
-      expect(isBigInt(TESTING_SYMBOL_STRING)).toBeFalse()
-    ))
-    .it(`'undefined'`, () => expect(isBigInt(TESTING_UNDEFINED)).toBeFalse())
-);
diff --git a/src/is/test/is-boolean-object.spec.ts b/src/is/test/is-boolean-object.spec.ts
deleted file mode 100644
index c2dead4c..00000000
--- a/src/is/test/is-boolean-object.spec.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-// Function.
-import { isBooleanObject } from '../lib/is-boolean-object.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.booleanObject.describe,
-  tests.is.booleanObject.it
-);
-/**
- * Tests.
- */
-testing.describe(isBooleanObject.name, () => {
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(isBooleanObject).toBeDefined())
-    .it(`Boolean`, () => {
-      expect(isBooleanObject(TESTING_FALSE_INSTANCE)).toBeTrue();
-      expect(isBooleanObject(TESTING_TRUE_INSTANCE)).toBeTrue();
-    })
-
-    // FALSE
-    .it(`boolean`, () => {
-      expect(isBooleanObject(TESTING_FALSE)).toBeFalse();
-      expect(isBooleanObject(TESTING_TRUE)).toBeFalse();
-      expect(isBooleanObject(Boolean(false))).toBeFalse();
-      expect(isBooleanObject(Boolean(true))).toBeFalse();
-    })
-    .it(`'bigint'`, () => {
-      expect(isBooleanObject(TESTING_BIGINT)).toBeFalse();
-      expect(isBooleanObject(TESTING_BIGINT)).toBeFalse();
-    })
-    .it(`TestingClass | TESTING_CLASS`, () => {
-      expect(isBooleanObject(TestingClass)).toBeFalse();
-      expect(isBooleanObject(TESTING_CLASS)).toBeFalse();
-    })
-    .it(`'function' | Function`, () => expect(isBooleanObject(TESTING_FUNCTION)).toBeFalse())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isBooleanObject(null)).toBeFalse();
-      expect(isBooleanObject(TESTING_NULL)).toBeFalse();
-    })
-    .it(`'number' | Number`, () => {
-      expect(isBooleanObject(TESTING_NUMBER)).toBeFalse();
-      expect(isBooleanObject(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse();
-      expect(isBooleanObject(TESTING_NUMBER_INSTANCE)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isBooleanObject(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isBooleanObject(TESTING_STRING)).toBeFalse();
-      expect(isBooleanObject(TESTING_STRING_CONSTRUCTOR)).toBeFalse();
-      expect(isBooleanObject(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isBooleanObject(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isBooleanObject(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => expect(isBooleanObject(TESTING_UNDEFINED)).toBeFalse());
-});
diff --git a/src/is/test/is-boolean-type.spec.ts b/src/is/test/is-boolean-type.spec.ts
deleted file mode 100644
index fb1d3cf3..00000000
--- a/src/is/test/is-boolean-type.spec.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-// Function.
-import { isBooleanType } from '../lib/is-boolean-type.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.booleanType.describe,
-  tests.is.booleanType.it
-);
-/**
- * Tests.
- */
-testing.describe(isBooleanType.name, () => {
-  // TRUE
-  testing
-    .it('is DEFINED', () => expect(isBooleanType).toBeDefined())
-    .it(`boolean`, () => {
-      expect(isBooleanType(TESTING_FALSE)).toBeTrue();
-      expect(isBooleanType(TESTING_TRUE)).toBeTrue();
-      expect(isBooleanType(Boolean(false))).toBeTrue();
-      expect(isBooleanType(Boolean(true))).toBeTrue();
-    })
-
-    // FALSE
-    .it(`Boolean`, () => {
-      expect(isBooleanType(TESTING_FALSE_INSTANCE)).toBeFalse();
-      expect(isBooleanType(TESTING_TRUE_INSTANCE)).toBeFalse();
-    })
-    .it(`'bigint'`, () => {
-      expect(isBooleanType(TESTING_BIGINT)).toBeFalse();
-      expect(isBooleanType(TESTING_BIGINT)).toBeFalse();
-    })
-    .it(`TestingClass | TESTING_CLASS`, () => {
-      expect(isBooleanType(TestingClass)).toBeFalse();
-      expect(isBooleanType(TESTING_CLASS)).toBeFalse();
-    })
-    .it(`'function' | Function`, () => expect(isBooleanType(TESTING_FUNCTION)).toBeFalse())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isBooleanType(null)).toBeFalse();
-      expect(isBooleanType(TESTING_NULL)).toBeFalse();
-    })
-    .it(`'number' | Number`, () => {
-      expect(isBooleanType(TESTING_NUMBER)).toBeFalse();
-      expect(isBooleanType(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse();
-      expect(isBooleanType(TESTING_NUMBER_INSTANCE)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isBooleanType(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isBooleanType(TESTING_STRING)).toBeFalse();
-      expect(isBooleanType(TESTING_STRING_CONSTRUCTOR)).toBeFalse();
-      expect(isBooleanType(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isBooleanType(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isBooleanType(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => expect(isBooleanType(TESTING_UNDEFINED)).toBeFalse());
-});
diff --git a/src/is/test/is-boolean.spec.ts b/src/is/test/is-boolean.spec.ts
deleted file mode 100644
index 4657f3bd..00000000
--- a/src/is/test/is-boolean.spec.ts
+++ /dev/null
@@ -1,94 +0,0 @@
-// Function.
-import { isBoolean } from '../lib/is-boolean.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.boolean.describe,
-  tests.is.boolean.it
-);
-/**
- * Tests.
- */
-testing.describe(isBoolean.name, () =>
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(isBoolean).toBeDefined())
-    .it(`'boolean' | Boolean`, () => {
-      expect(isBoolean(TESTING_FALSE)).toBeTrue();
-      expect(isBoolean(TESTING_TRUE)).toBeTrue();
-      expect(isBoolean(TESTING_FALSE_INSTANCE)).toBeTrue();
-      expect(isBoolean(TESTING_TRUE_INSTANCE)).toBeTrue();
-      expect(isBoolean(Boolean(false))).toBeTrue();
-      expect(isBoolean(Boolean(true))).toBeTrue();
-      isBoolean(TESTING_FALSE, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      });
-    })
-
-    // FALSE
-    .it(`'bigint'`, () => {
-      expect(isBoolean(TESTING_BIGINT)).toBeFalse();
-      expect(isBoolean(TESTING_BIGINT)).toBeFalse();
-      isBoolean(TESTING_BIGINT, (result: boolean) => {
-        expect(result).toBeFalse();
-        return result;
-      });
-    })
-    .it(`TestingClass | TESTING_CLASS`, () => {
-      expect(isBoolean(TestingClass)).toBeFalse();
-      expect(isBoolean(TESTING_CLASS)).toBeFalse();
-    })
-    .it(`'function' | Function`, () => expect(isBoolean(TESTING_FUNCTION)).toBeFalse())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isBoolean(null)).toBeFalse();
-      expect(isBoolean(TESTING_NULL)).toBeFalse();
-    })
-    .it(`'number' | Number`, () => {
-      expect(isBoolean(TESTING_NUMBER)).toBeFalse();
-      expect(isBoolean(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse();
-      expect(isBoolean(TESTING_NUMBER_INSTANCE)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isBoolean(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isBoolean(TESTING_STRING)).toBeFalse();
-      expect(isBoolean(TESTING_STRING_CONSTRUCTOR)).toBeFalse();
-      expect(isBoolean(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isBoolean(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isBoolean(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => expect(isBoolean(TESTING_UNDEFINED)).toBeFalse())
-);
diff --git a/src/is/test/is-class.spec.ts b/src/is/test/is-class.spec.ts
deleted file mode 100644
index 1f7944f4..00000000
--- a/src/is/test/is-class.spec.ts
+++ /dev/null
@@ -1,123 +0,0 @@
-// Function.
-import { isClass } from '../lib/is-class.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.class.describe,
-  tests.is.class.it
-);
-/**
- * Tests.
- */
-testing.describe(isClass.name, () => {
-  // Defined.
-  testing.it('is DEFINED', () => expect(isClass).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing.it('callback', () => {
-      isClass(TestingClass, (result, value, payload) => {
-        expect(result).toBeTrue();
-        if (payload) {
-          expect(value).toEqual(TestingClass);
-        }
-        return result;
-      });
-    })
-    // ... arrays.
-    .describe(`array`, () => { })
-    // ... function.
-    .describe(`function`, () => {
-      testing
-        .it(`TESTING_FUNCTION`, () => expect(isClass(TESTING_FUNCTION)).toBeFalse())
-        .it(`TestingClass`, () => expect(isClass(TestingClass)).toBeTrue());
-    })
-    // ... objects.
-    .describe('object', () => {
-      testing
-        .it(`TESTING_CLASS`, () => expect(isClass(TESTING_CLASS)).toBeFalse())
-        .it(`TESTING_OBJECT`, () => expect(isClass(TESTING_OBJECT)).toBeFalse())
-        .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isClass(TESTING_OBJECT)).toBeFalse());
-    })
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-        // bigint
-        .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isClass(TESTING_BIGINT)).toBeFalse()))
-        // boolean
-        .describe(`boolean`, () => {
-          testing
-            .it(`${TESTING_TRUE}`, () => expect(isClass(TESTING_TRUE)).toBeFalse())
-            .it(`${TESTING_FALSE}`, () => expect(isClass(TESTING_FALSE)).toBeFalse());
-        })
-        // null
-        .it(`${TESTING_NULL}`, () => expect(isClass(TESTING_NULL)).toBeFalse())
-        // number
-        .describe(`number`, () => {
-          testing
-            .it(`${TESTING_NUMBER}`, () => expect(isClass(TESTING_NUMBER)).toBeFalse())
-            .it(`Number(${TESTING_NUMBER})`, () => expect(isClass(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-        })
-        // string
-        .describe(`string`, () => {
-          testing
-            .it(`${TESTING_STRING}`, () => expect(isClass(TESTING_STRING)).toBeFalse())
-            .it(`String(${TESTING_STRING})`, () => expect(isClass(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-        })
-        // symbol
-        .describe(`symbol`, () => {
-          testing
-            .it(`Symbol(${TESTING_NUMBER})`, () => expect(isClass(TESTING_SYMBOL_NUMBER)).toBeFalse())
-            .it(`Symbol(${TESTING_STRING})`, () => expect(isClass(TESTING_SYMBOL_STRING)).toBeFalse());
-        })
-        // undefined
-        .it(`${TESTING_UNDEFINED}`, () => expect(isClass(TESTING_UNDEFINED)).toBeFalse())
-        // ... object.
-        .describe(`object`, () => {
-          testing
-            // BigInt
-            .describe(`BigInt`, () => it(`${TESTING_BIGINT}`, () => expect(isClass(TESTING_BIGINT)).toBeFalse()))
-            // Boolean
-            .describe(`Boolean`, () => {
-              it(`${TESTING_TRUE_INSTANCE}`, () => expect(isClass(TESTING_TRUE_INSTANCE)).toBeFalse());
-              it(`${TESTING_FALSE_INSTANCE}`, () => expect(isClass(TESTING_FALSE_INSTANCE)).toBeFalse());
-            })
-            // Number
-            .describe(`Number`, () => it(`new Number(${TESTING_NUMBER})`, () => expect(isClass(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-            // String
-            .describe(`String`, () => it(`new String(${TESTING_STRING})`, () => expect(isClass(TESTING_STRING_INSTANCE)).toBeFalse()));
-        });
-    });
-  });
-});
diff --git a/src/is/test/is-date.spec.ts b/src/is/test/is-date.spec.ts
deleted file mode 100644
index 8b36b943..00000000
--- a/src/is/test/is-date.spec.ts
+++ /dev/null
@@ -1,130 +0,0 @@
-// Function.
-import { isDate } from '../lib/is-date.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.date.describe,
-  tests.is.date.it)
-;
-/**
- * Tests.
- */
-testing.describe(isDate.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isDate).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing.it('callback', () => {
-        isDate(TESTING_DATE, (result: boolean) => {
-          expect(result).toBeTrue();
-          return result;
-        });
-      })
-      // ... arrays.
-      .describe(`array`, () => { })
-      // ... Date.
-      .describe(`date`, () => {
-        testing
-          .it(`TESTING_DATE`, () => expect(isDate(TESTING_DATE)).toBeTrue())
-      })
-      // ... function.
-      .describe(`function`, () => {
-        testing
-          .it(`TESTING_FUNCTION`, () => expect(isDate(TESTING_FUNCTION)).toBeFalse())
-          .it(`TestingClass`, () => expect(isDate(TestingClass)).toBeFalse());
-      })
-      // ... objects.
-      .describe('object', () => {
-        testing
-          .it(`TESTING_CLASS`, () => expect(isDate(TESTING_CLASS)).toBeFalse())
-          .it(`TESTING_OBJECT`, () => expect(isDate(TESTING_OBJECT)).toBeFalse())
-          .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isDate(TESTING_OBJECT)).toBeFalse());
-      })
-      // ... primitives.
-      .describe(`primitive`, () => {
-        testing
-          // bigint
-          .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isDate(TESTING_BIGINT)).toBeFalse()))
-          // boolean
-          .describe(`boolean`, () => {
-            testing
-              .it(`${TESTING_TRUE}`, () => expect(isDate(TESTING_TRUE)).toBeFalse())
-              .it(`${TESTING_FALSE}`, () => expect(isDate(TESTING_FALSE)).toBeFalse());
-          })
-          // null
-          .it(`${TESTING_NULL}`, () => expect(isDate(TESTING_NULL)).toBeFalse())
-          // number
-          .describe(`number`, () => {
-            testing
-              .it(`${TESTING_NUMBER}`, () => expect(isDate(TESTING_NUMBER)).toBeFalse())
-              .it(`Number(${TESTING_NUMBER})`, () => expect(isDate(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-          })
-          // string
-          .describe(`string`, () => {
-            testing
-              .it(`${TESTING_STRING}`, () => expect(isDate(TESTING_STRING)).toBeFalse())
-              .it(`String(${TESTING_STRING})`, () => expect(isDate(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-          })
-          // symbol
-          .describe(`symbol`, () => {
-            testing
-              .it(`Symbol(${TESTING_NUMBER})`, () => expect(isDate(TESTING_SYMBOL_NUMBER)).toBeFalse())
-              .it(`Symbol(${TESTING_STRING})`, () => expect(isDate(TESTING_SYMBOL_STRING)).toBeFalse());
-          })
-          // undefined
-          .it(`${TESTING_UNDEFINED}`, () => expect(isDate(TESTING_UNDEFINED)).toBeFalse())
-          // ... object.
-          .describe(`object`, () => {
-            testing.
-              // BigInt
-              describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isDate(TESTING_BIGINT)).toBeFalse()))
-              // Boolean
-              .describe(`Boolean`, () => {
-                testing
-                  .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isDate(TESTING_TRUE_INSTANCE)).toBeFalse())
-                  .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isDate(TESTING_FALSE_INSTANCE)).toBeFalse());
-              })
-              // Number
-              .describe(`Number`, () =>
-                testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isDate(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-              // String
-              .describe(`String`, () =>
-                testing.it(`new String(${TESTING_STRING})`, () => expect(isDate(TESTING_STRING_INSTANCE)).toBeFalse()));
-          });
-      });
-    });
-});
diff --git a/src/is/test/is-defined.spec.ts b/src/is/test/is-defined.spec.ts
deleted file mode 100644
index 1d709566..00000000
--- a/src/is/test/is-defined.spec.ts
+++ /dev/null
@@ -1,96 +0,0 @@
-// Function.
-import { isDefined } from '../lib/is-defined.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.defined.describe,
-  tests.is.defined.it
-);
-/**
- * Tests.
- */
-testing.describe(isDefined.name, () => {
-  // TRUE
-  testing
-    .it('is DEFINED', () => expect(isDefined).toBeDefined())
-    .it(`'boolean' | Boolean`, () => {
-      expect(isDefined(TESTING_FALSE)).toBeTrue();
-      expect(isDefined(TESTING_TRUE)).toBeTrue();
-      expect(isDefined(TESTING_FALSE_INSTANCE)).toBeTrue();
-      expect(isDefined(TESTING_TRUE_INSTANCE)).toBeTrue();
-      expect(isDefined(Boolean(false))).toBeTrue();
-      expect(isDefined(Boolean(true))).toBeTrue();
-      isDefined(TESTING_FALSE, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      });
-    })
-    .it(`'bigint'`, () => expect(isDefined(TESTING_BIGINT)).toBeTrue())
-    .it(`TestingClass | TESTING_CLASS`, () => {
-      expect(isDefined(TestingClass)).toBeTrue();
-      expect(isDefined(TESTING_CLASS)).toBeTrue();
-    })
-    .it(`'function' | Function`, () => expect(isDefined(TESTING_FUNCTION)).toBeTrue())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isDefined(null)).toBeTrue();
-      expect(isDefined(TESTING_NULL)).toBeTrue();
-    })
-    .it(`'number' | Number`, () => {
-      expect(isDefined(TESTING_NUMBER)).toBeTrue();
-      expect(isDefined(TESTING_NUMBER_CONSTRUCTOR)).toBeTrue();
-      expect(isDefined(TESTING_NUMBER_INSTANCE)).toBeTrue();
-    })
-    .it(`'object' | Object`, () => expect(isDefined(TESTING_OBJECT)).toBeTrue())
-    .it(`'string' | String`, () => {
-      expect(isDefined(TESTING_STRING)).toBeTrue();
-      expect(isDefined(TESTING_STRING_CONSTRUCTOR)).toBeTrue();
-      expect(isDefined(TESTING_STRING_INSTANCE)).toBeTrue();
-    })
-    .it(`'symbol'`, () => {
-      expect(isDefined(TESTING_SYMBOL_NUMBER)).toBeTrue();
-      expect(isDefined(TESTING_SYMBOL_STRING)).toBeTrue();
-    })
-
-    // FALSE
-    .it(`'undefined'`, () => {
-      expect(isDefined(TESTING_UNDEFINED)).toBeFalse();
-      isDefined(TESTING_UNDEFINED, (result, value, payload) => {
-        expect(result).toBeFalse();
-        if (payload) {
-          expect(value).toBeUndefined();
-        }
-        return result;
-      });
-    });
-});
diff --git a/src/is/test/is-false.spec.ts b/src/is/test/is-false.spec.ts
deleted file mode 100644
index 9210b7bb..00000000
--- a/src/is/test/is-false.spec.ts
+++ /dev/null
@@ -1,129 +0,0 @@
-// Function.
-import { isFalse } from '../lib/is-false.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.false.describe,
-  tests.is.false.it
-);
-/**
- * Tests.
- */
-testing.describe(isFalse.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isFalse).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isFalse(TESTING_FALSE, (result: boolean) => {
-            expect(result).toBeTrue();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => { })
-        // ... Date.
-        .describe(`date`, () => {
-          testing
-            .it(`TESTING_DATE`, () => expect(isFalse(TESTING_DATE)).toBeFalse())
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isFalse(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isFalse(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isFalse(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isFalse(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isFalse(TESTING_OBJECT)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isFalse(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isFalse(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isFalse(TESTING_FALSE)).toBeTrue());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isFalse(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isFalse(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isFalse(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isFalse(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isFalse(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isFalse(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isFalse(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isFalse(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => it(`${TESTING_BIGINT}`, () => expect(isFalse(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isFalse(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isFalse(TESTING_FALSE_INSTANCE)).toBeTrue());
-                })
-                // Number
-                .describe(`Number`, () => it(`new Number(${TESTING_NUMBER})`, () => expect(isFalse(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () => it(`new String(${TESTING_STRING})`, () => expect(isFalse(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-function.spec.ts b/src/is/test/is-function.spec.ts
deleted file mode 100644
index 0cf5d060..00000000
--- a/src/is/test/is-function.spec.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-// Function.
-import { isFunction } from '../lib/is-function.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.function.describe,
-  tests.is.function.it
-);
-/**
- * Tests.
- */
-testing.describe(isFunction.name, () => {
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(isFunction).toBeDefined())
-    .it(`'function' | Function`, () => expect(isFunction(TESTING_FUNCTION)).toBeTrue())
-
-    // FALSE.
-    .it(`'boolean' | Boolean`, () => {
-      expect(isFunction(TESTING_FALSE)).toBeFalse();
-      expect(isFunction(TESTING_TRUE)).toBeFalse();
-      expect(isFunction(TESTING_FALSE_INSTANCE)).toBeFalse();
-      expect(isFunction(TESTING_TRUE_INSTANCE)).toBeFalse();
-      expect(isFunction(Boolean(false))).toBeFalse();
-      expect(isFunction(Boolean(true))).toBeFalse();
-      isFunction(TESTING_TRUE, (result: boolean) => {
-        expect(result).toBeFalse();
-        return result;
-      });
-    })
-    .it(`'bigint'`, () => {
-      expect(isFunction(TESTING_BIGINT)).toBeFalse();
-      expect(isFunction(TESTING_BIGINT)).toBeFalse();
-    })
-    .it(`TESTING_CLASS`, () => expect(isFunction(TESTING_CLASS)).toBeFalse())
-    .it(`TestingClass`, () => expect(isFunction(TestingClass)).toBeFalse())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isFunction(null)).toBeFalse();
-      expect(isFunction(TESTING_NULL)).toBeFalse();
-    })
-    .it(`'number' | Number`, () => {
-      expect(isFunction(TESTING_NUMBER)).toBeFalse();
-      expect(isFunction(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse();
-      expect(isFunction(TESTING_NUMBER_INSTANCE)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isFunction(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isFunction(TESTING_STRING)).toBeFalse();
-      expect(isFunction(TESTING_STRING_CONSTRUCTOR)).toBeFalse();
-      expect(isFunction(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isFunction(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isFunction(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => expect(isFunction(TESTING_UNDEFINED)).toBeFalse());
-});
diff --git a/src/is/test/is-instance.spec.ts b/src/is/test/is-instance.spec.ts
deleted file mode 100644
index f258b217..00000000
--- a/src/is/test/is-instance.spec.ts
+++ /dev/null
@@ -1,92 +0,0 @@
-// Function.
-import { isInstance } from '../lib/is-instance.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_FUNCTION_CONSTRUCTOR,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_PERSON,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-  TestingPerson,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.instance.describe,
-  tests.is.instance.it
-);
-/**
- * Tests.
- */
-testing.describe(isInstance.name, () => {
-  const anyInstance: any = new (TESTING_FUNCTION_CONSTRUCTOR as any)('First name', 'Sur name', 27);
-  testing
-    // TRUE.
-    .it('is DEFINED', () => expect(isInstance).toBeDefined())
-    .it(`CLASS instance of Class`, () => expect(isInstance(TESTING_CLASS, TestingClass)).toBeTrue())
-    .it(`PERSON instance of Person`, () => expect(isInstance(TESTING_PERSON, TestingPerson)).toBeTrue())
-    .it(`CLASS instance of Class expect result to be true`, () => {
-      isInstance(TESTING_CLASS, TestingClass, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      });
-    })
-    .it(`function constructor`, () => expect(isInstance(anyInstance, TESTING_FUNCTION_CONSTRUCTOR as any)).toBeTrue())
-
-    // FALSE.
-    .it(`PERSON_COPY not instance of Person`, () => {
-      class TestingPersonCopy {
-        firstName = '';
-        surname = '';
-        age = 15;
-      }
-      expect(isInstance(new TestingPersonCopy(), TestingPerson)).toBeFalse();
-    })
-    .it(`'boolean' | Boolean`, () => {
-      expect(isInstance(TESTING_FALSE, TESTING_FALSE as any)).toBeFalse();
-      expect(isInstance(TESTING_TRUE, TESTING_TRUE as any)).toBeFalse();
-      expect(isInstance(TESTING_FALSE_INSTANCE, TESTING_FALSE_INSTANCE as any)).toBeFalse();
-      expect(isInstance(TESTING_TRUE_INSTANCE, TESTING_TRUE_INSTANCE as any)).toBeFalse();
-    })
-    .it(`'bigint'`, () => expect(isInstance(TESTING_BIGINT, TESTING_BIGINT as any)).toBeFalse())
-    .it(`TestingClass`, () => expect(isInstance(TestingClass, TestingClass)).toBeFalse())
-    .it(`FUNCTION instance of Function`, () => expect(isInstance(TESTING_FUNCTION, Function)).toBeFalse())
-    .it(`NULL`, () => expect(isInstance(TESTING_NULL, TESTING_NULL as any)).toBeFalse())
-    .it(`'number' | Number`, () => {
-      expect(isInstance(TESTING_NUMBER, TESTING_NUMBER as any)).toBeFalse();
-      expect(isInstance(TESTING_NUMBER_INSTANCE, TESTING_NUMBER_CONSTRUCTOR as any)).toBeFalse();
-      expect(isInstance(TESTING_NUMBER_INSTANCE, TESTING_NUMBER_INSTANCE as any)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isInstance(TESTING_OBJECT, TESTING_OBJECT as any)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isInstance(TESTING_STRING, TESTING_STRING as any)).toBeFalse();
-      expect(isInstance(TESTING_STRING_INSTANCE, TESTING_STRING_CONSTRUCTOR as any)).toBeFalse();
-      expect(isInstance(TESTING_STRING_INSTANCE, TESTING_STRING_INSTANCE as any)).toBeFalse();
-    })
-
-    // FALSE
-    .it(`undefined`, () => expect(isInstance(TESTING_UNDEFINED, TESTING_UNDEFINED as any)).toBeFalse());
-});
diff --git a/src/is/test/is-key.spec.ts b/src/is/test/is-key.spec.ts
deleted file mode 100644
index 72d65e12..00000000
--- a/src/is/test/is-key.spec.ts
+++ /dev/null
@@ -1,125 +0,0 @@
-// Function.
-import { isKey } from '../lib/is-key.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.key.describe,
-  tests.is.key.it
-);
-/**
- * Tests.
- */
-testing.describe(isKey.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isKey).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isKey('test', (result: boolean) => {
-            expect(result).toBeTrue();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => { })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isKey(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isKey(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isKey(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isKey(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isKey(TESTING_OBJECT)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isKey(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isKey(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isKey(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isKey(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isKey(TESTING_NUMBER)).toBeTrue())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isKey(TESTING_NUMBER_CONSTRUCTOR)).toBeTrue());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isKey(TESTING_STRING)).toBeTrue())
-                .it(`String(${TESTING_STRING})`, () => expect(isKey(TESTING_STRING_CONSTRUCTOR)).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isKey(TESTING_SYMBOL_NUMBER)).toBeTrue())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isKey(TESTING_SYMBOL_STRING)).toBeTrue());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isKey(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isKey(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isKey(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isKey(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isKey(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isKey(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-null.spec.ts b/src/is/test/is-null.spec.ts
deleted file mode 100644
index 555d3039..00000000
--- a/src/is/test/is-null.spec.ts
+++ /dev/null
@@ -1,91 +0,0 @@
-// Function.
-import { isNull } from '../lib/is-null.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constants.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.null.describe,
-  tests.is.null.it
-);
-/**
- * Tests.
- */
-testing.describe(isNull.name, () => {
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(isNull).toBeDefined())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isNull(null)).toBeTrue();
-      expect(isNull(TESTING_NULL)).toBeTrue();
-      isNull(TESTING_NULL, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      });
-    })
-    // FALSE
-    .it(`'bigint'`, () => {
-      expect(isNull(TESTING_BIGINT)).toBeFalse();
-      expect(isNull(TESTING_BIGINT)).toBeFalse();
-    })
-    .it(`'boolean' | Boolean`, () => {
-      expect(isNull(TESTING_FALSE)).toBeFalse();
-      expect(isNull(TESTING_TRUE)).toBeFalse();
-      expect(isNull(TESTING_FALSE_INSTANCE)).toBeFalse();
-      expect(isNull(TESTING_TRUE_INSTANCE)).toBeFalse();
-      expect(isNull(Boolean(false))).toBeFalse();
-      expect(isNull(Boolean(true))).toBeFalse();
-    })
-    .it(`TestingClass | TESTING_CLASS`, () => {
-      expect(isNull(TestingClass)).toBeFalse();
-      expect(isNull(TESTING_CLASS)).toBeFalse();
-    })
-    .it(`'function' | Function`, () => expect(isNull(TESTING_FUNCTION)).toBeFalse())
-    .it(`'number' | Number`, () => {
-      expect(isNull(TESTING_NUMBER)).toBeFalse();
-      expect(isNull(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse();
-      expect(isNull(TESTING_NUMBER_INSTANCE)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isNull(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isNull(TESTING_STRING)).toBeFalse();
-      expect(isNull(TESTING_STRING_CONSTRUCTOR)).toBeFalse();
-      expect(isNull(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isNull(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isNull(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => {
-      expect(isNull(TESTING_UNDEFINED)).toBeFalse();
-    });
-});
diff --git a/src/is/test/is-number-between.spec.ts b/src/is/test/is-number-between.spec.ts
deleted file mode 100644
index ba9c1353..00000000
--- a/src/is/test/is-number-between.spec.ts
+++ /dev/null
@@ -1,138 +0,0 @@
-// Function.
-import { isNumberBetween } from '../lib/is-number-between.func';
-// Testing.
-import {
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  Testing,
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.numberBetween.describe,
-  tests.is.numberBetween.it
-);
-/**
- * Tests.
- */
-testing.describe(isNumberBetween.name, () => {
-  // Constant.
-  const min = 0;
-  const max = 13;
-  const value = 13;
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isNumberBetween).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isNumberBetween(TESTING_FALSE,  min, max, (result: boolean) => {
-            expect(result).toBeFalse();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => { })
-        // ... Date.
-        .describe(`date`, () => {
-          testing
-          .it(`TESTING_DATE`, () => expect(isNumberBetween(TESTING_DATE,  min, max)).toBeFalse());
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isNumberBetween(TESTING_FUNCTION,  min, max)).toBeFalse())
-            .it(`TestingClass`, () => expect(isNumberBetween(TestingClass,  min, max)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isNumberBetween(TESTING_CLASS,  min, max)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isNumberBetween(TESTING_OBJECT,  min, max)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () =>
-              testing.it(`${TESTING_BIGINT}`, () => expect(isNumberBetween(TESTING_BIGINT,  min, max)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isNumberBetween(TESTING_TRUE,  min, max)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isNumberBetween(TESTING_FALSE,  min, max)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isNumberBetween(TESTING_NULL,  min, max)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isNumberBetween(TESTING_NUMBER,  min, max)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isNumberBetween(TESTING_NUMBER_INSTANCE,  min, max)).toBeFalse())
-                .it(`${TESTING_NUMBER}`, () => expect(isNumberBetween(value,  min, max)).toBeTrue());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isNumberBetween(TESTING_STRING,  min, max)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isNumberBetween(TESTING_STRING_INSTANCE,  min, max)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNumberBetween(TESTING_SYMBOL_NUMBER,  min, max)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isNumberBetween(TESTING_SYMBOL_STRING,  min, max)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isNumberBetween(TESTING_UNDEFINED,  min, max)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () =>
-                  testing.it(`${TESTING_BIGINT}`, () => expect(isNumberBetween(TESTING_BIGINT,  min, max)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNumberBetween(TESTING_TRUE_INSTANCE,  min, max)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNumberBetween(TESTING_FALSE_INSTANCE,  min, max)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () => {
-                  testing
-                    .it(`new Number(${TESTING_NUMBER})`, () => expect(isNumberBetween(TESTING_NUMBER_INSTANCE,  min, max)).toBeFalse())
-                    .it(`new Number(${value})`, () => expect(isNumberBetween(new Number(value),  min, max)).toBeTrue())
-                    .it(`new Number(${value})`, () => expect(isNumberBetween(new Number(1.15),  min, max)).toBeTrue())
-                    .it(`new Number(${value})`, () => expect(isNumberBetween(new Number(13.15),  min, max)).toBeFalse());
-                })
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () =>
-                    expect(isNumberBetween(TESTING_STRING_INSTANCE,  min, max)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-number-object.spec.ts b/src/is/test/is-number-object.spec.ts
deleted file mode 100644
index 371eb443..00000000
--- a/src/is/test/is-number-object.spec.ts
+++ /dev/null
@@ -1,120 +0,0 @@
-// Function.
-import { isNumberObject } from '../lib/is-number-object.func';
-// Testing.
-import {
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  Testing,
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.numberObject.describe,
-  tests.is.numberObject.it
-);
-/**
- * Checks
- * ✓ typeof === 'object' && instanceof Number === true && instanceof Object === true
- */
-testing.describe(isNumberObject.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isNumberObject).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isNumberObject(TESTING_NUMBER_INSTANCE, (result: boolean) => {
-            expect(result).toBeTrue();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => { })
-        // ... function.
-        .describe(`function`, () => testing
-          .it(`TESTING_FUNCTION`, () => expect(isNumberObject(TESTING_FUNCTION)).toBeFalse())
-          .it(`TestingClass`, () => expect(isNumberObject(TestingClass)).toBeFalse())
-        )
-        // ... objects.
-        .describe('object', () => testing
-          .it(`TESTING_CLASS`, () => expect(isNumberObject(TESTING_CLASS)).toBeFalse())
-          .it(`TESTING_OBJECT`, () => expect(isNumberObject(TESTING_OBJECT)).toBeFalse())
-          .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isNumberObject(TESTING_OBJECT)).toBeFalse())
-        )
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isNumberObject(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isNumberObject(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isNumberObject(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isNumberObject(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isNumberObject(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isNumberObject(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isNumberObject(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isNumberObject(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNumberObject(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isNumberObject(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isNumberObject(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isNumberObject(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNumberObject(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNumberObject(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isNumberObject(TESTING_NUMBER_INSTANCE)).toBeTrue()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isNumberObject(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-number-type.spec.ts b/src/is/test/is-number-type.spec.ts
deleted file mode 100644
index b61fb1bd..00000000
--- a/src/is/test/is-number-type.spec.ts
+++ /dev/null
@@ -1,124 +0,0 @@
-// Function.
-import { isNumberType } from '../lib/is-number-type.func';
-// Testing.
-import {
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  Testing,
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.numberType.describe,
-  tests.is.numberType.it
-);
-/**
- * Checks
- * ✓ typeof === 'number' && instanceof Number === false && instanceof Object === false
- * ✓ value === true
- * ✓ value === false
- */
-testing.describe(isNumberType.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isNumberType).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isNumberType(TESTING_NUMBER, (result: boolean) => {
-            expect(result).toBeTrue();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => { })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isNumberType(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isNumberType(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isNumberType(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isNumberType(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isNumberType(TESTING_OBJECT)).toBeFalse())
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isNumberType(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isNumberType(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isNumberType(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isNumberType(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isNumberType(TESTING_NUMBER)).toBeTrue())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isNumberType(TESTING_NUMBER_CONSTRUCTOR)).toBeTrue());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isNumberType(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isNumberType(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isNumberType(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isNumberType(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isNumberType(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isNumberType(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isNumberType(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isNumberType(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isNumberType(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isNumberType(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-number.spec.ts b/src/is/test/is-number.spec.ts
deleted file mode 100644
index 0e1ac0f9..00000000
--- a/src/is/test/is-number.spec.ts
+++ /dev/null
@@ -1,88 +0,0 @@
-// Function.
-import { isNumber } from '../lib/is-number.func';
-// Testing.
-import {
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  Testing,
-  TestingClass,
-} from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.number.describe,
-  tests.is.number.it
-);
-/**
- * Checks
- * ✓ typeof === 'number'
- * ✓ instanceof Number
- *
- * ✓ typeof === 'object'
- * ✓ instanceof Object
- */
-testing.describe(isNumber.name, () => {
-  testing
-    // TRUE
-    .it('is DEFINED', () => expect(isNumber).toBeDefined())
-    .it(`'number' | Number`, () => {
-      expect(isNumber(TESTING_NUMBER)).toBeTrue();
-      expect(isNumber(TESTING_NUMBER_CONSTRUCTOR)).toBeTrue();
-      expect(isNumber(TESTING_NUMBER_INSTANCE)).toBeTrue();
-      isNumber(TESTING_NUMBER_INSTANCE, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      });
-    })
-
-    // FALSE
-    .it(`'bigint'`, () => {
-      expect(isNumber(TESTING_BIGINT)).toBeFalse();
-      expect(isNumber(TESTING_BIGINT)).toBeFalse();
-    })
-    .it(`'boolean' | Boolean`, () => {
-      expect(isNumber(TESTING_FALSE)).toBeFalse();
-      expect(isNumber(TESTING_TRUE)).toBeFalse();
-      expect(isNumber(TESTING_FALSE_INSTANCE)).toBeFalse();
-      expect(isNumber(TESTING_TRUE_INSTANCE)).toBeFalse();
-    })
-    .it(`TestingClass | TESTING_CLASS`, () => {
-      expect(isNumber(TestingClass)).toBeFalse();
-      expect(isNumber(TESTING_CLASS)).toBeFalse();
-    })
-    .it(`'function' | Function`, () => expect(isNumber(TESTING_FUNCTION)).toBeFalse())
-    .it(`null | TESTING_NULL`, () => {
-      expect(isNumber(null)).toBeFalse();
-      expect(isNumber(TESTING_NULL)).toBeFalse();
-    })
-    .it(`'object' | Object`, () => expect(isNumber(TESTING_OBJECT)).toBeFalse())
-    .it(`'string' | String`, () => {
-      expect(isNumber(TESTING_STRING)).toBeFalse();
-      expect(isNumber(TESTING_STRING_CONSTRUCTOR)).toBeFalse();
-      expect(isNumber(TESTING_STRING_INSTANCE)).toBeFalse();
-    })
-    .it(`'symbol'`, () => {
-      expect(isNumber(TESTING_SYMBOL_NUMBER)).toBeFalse();
-      expect(isNumber(TESTING_SYMBOL_STRING)).toBeFalse();
-    })
-    .it(`'undefined'`, () => expect(isNumber(TESTING_UNDEFINED)).toBeFalse());
-});
diff --git a/src/is/test/is-object-key-in.spec.ts b/src/is/test/is-object-key-in.spec.ts
deleted file mode 100644
index 627b8d09..00000000
--- a/src/is/test/is-object-key-in.spec.ts
+++ /dev/null
@@ -1,152 +0,0 @@
-// Function.
-import { isObjectKeyIn } from '../lib/is-object-key-in.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.objectKeyIn.describe,
-  tests.is.objectKeyIn.it
-);
-/**
- * Tests.
- */
-testing.describe(isObjectKeyIn.name , () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isObjectKeyIn).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isObjectKeyIn(TESTING_CLASS, 'firstName', (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_CLASS);
-            }
-            return result;
-          });
-        })
-        // ... instance.
-        .describe(`instance`, () => testing
-          .describe(`TESTING_CLASS`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectKeyIn(TESTING_CLASS, 1030405027)).toBeTrue();
-              expect(isObjectKeyIn(TESTING_CLASS, 5)).toBeTrue();
-              expect(isObjectKeyIn(TESTING_CLASS, TESTING_NUMBER)).toBeTrue(); // It does find getter number
-            })
-            // string.
-            .it('has string key', () => {
-              expect(isObjectKeyIn(TESTING_CLASS, 'surname')).toBeTrue();
-            })
-            // symbol.
-            .it('has getter symbol key', () => {
-              // It does find getter symbol key
-              expect(isObjectKeyIn(TESTING_CLASS, TESTING_SYMBOL_NUMBER)).toBeTrue();
-              expect(isObjectKeyIn(TESTING_CLASS, TESTING_SYMBOL_STRING)).toBeTrue();
-            })
-          )
-        )
-        // ... function.
-        .describe(`function`, () => testing
-          .it(`TESTING_FUNCTION`, () => expect(isObjectKeyIn(TESTING_FUNCTION, 'function')).toBeFalse())
-          .it(`TESTING_CLASS`, () => expect(isObjectKeyIn(TestingClass, 'function')).toBeFalse())
-        )
-        // ... objects.
-        .describe('object', () => testing
-          .describe(`TESTING_OBJECT`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectKeyIn(TESTING_OBJECT, 1030405027)).toBeTrue();
-              expect(isObjectKeyIn(TESTING_OBJECT, 5)).toBeTrue();
-              expect(isObjectKeyIn(TESTING_OBJECT, TESTING_NUMBER)).toBeTrue(); // It doesn't find getter
-            })
-            // string.
-            .it('has string key', () => {
-              expect(isObjectKeyIn(TESTING_OBJECT, 'key as string')).toBeTrue();
-              expect(isObjectKeyIn(TESTING_OBJECT, 'x')).toBeTrue();
-              expect(isObjectKeyIn(TESTING_OBJECT, TESTING_STRING)).toBeTrue();
-            })
-            // symbol.
-            .it('has symbol key', () => {
-              expect(isObjectKeyIn(TESTING_OBJECT, TESTING_SYMBOL_NUMBER)).toBeTrue();
-              expect(isObjectKeyIn(TESTING_OBJECT, TESTING_SYMBOL_STRING)).toBeTrue();
-            })
-          )
-        )
-        // ... primitives.
-        .describe(`primitive`, () => testing
-          // bigint
-          .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKeyIn(TESTING_BIGINT, 'bigint')).toBeFalse()))
-          // boolean
-          .describe(`boolean`, () => testing
-            .it(`${TESTING_TRUE}`, () => expect(isObjectKeyIn(TESTING_TRUE, 'boolean')).toBeFalse())
-            .it(`${TESTING_FALSE}`, () => expect(isObjectKeyIn(TESTING_FALSE, 'boolean')).toBeFalse())
-          )
-          // null
-          .it(`${TESTING_NULL}`, () => expect(isObjectKeyIn(TESTING_NULL, 'null')).toBeFalse())
-          // number
-          .describe(`number`, () => testing
-            .it(`${TESTING_NUMBER}`, () => expect(isObjectKeyIn(TESTING_NUMBER, 'number')).toBeFalse())
-            .it(`Number(${TESTING_NUMBER})`, () => expect(isObjectKeyIn(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse())
-          )
-          // string
-          .describe(`string`, () => testing
-            .it(`${TESTING_STRING}`, () => expect(isObjectKeyIn(TESTING_STRING, 'string')).toBeFalse())
-            .it(`String(${TESTING_STRING})`, () => expect(isObjectKeyIn(TESTING_STRING_INSTANCE, 'string')).toBeFalse())
-          )
-          // symbol
-          .describe(`symbol`, () => testing
-            .it(`Symbol(${TESTING_NUMBER})`, () => expect(isObjectKeyIn(TESTING_SYMBOL_NUMBER, 'symbol')).toBeFalse())
-            .it(`Symbol(${TESTING_STRING})`, () => expect(isObjectKeyIn(TESTING_SYMBOL_STRING, 'symbol')).toBeFalse())
-          )
-          // undefined
-          .it(`${TESTING_UNDEFINED}`, () => expect(isObjectKeyIn(TESTING_UNDEFINED, 'undefined')).toBeFalse())
-          // ... object.
-          .describe(`object`, () => testing
-            // BigInt
-            .describe(`BigInt`, () =>
-              testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKeyIn(TESTING_BIGINT, 'bigint')).toBeFalse()))
-            // Boolean
-            .describe(`Boolean`, () => testing
-              .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isObjectKeyIn(TESTING_TRUE_INSTANCE, 'boolean')).toBeFalse())
-              .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isObjectKeyIn(TESTING_FALSE_INSTANCE, 'boolean')).toBeFalse())
-            )
-            // Number
-            .describe(`Number`, () =>
-              testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isObjectKeyIn(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse()))
-            // String
-            .describe(`String`, () =>
-              testing.it(`new String(${TESTING_STRING})`, () => expect(isObjectKeyIn(TESTING_STRING_INSTANCE, 'string')).toBeFalse()))
-          )
-        );
-    });
-});
diff --git a/src/is/test/is-object-key.spec.ts b/src/is/test/is-object-key.spec.ts
deleted file mode 100644
index ce271816..00000000
--- a/src/is/test/is-object-key.spec.ts
+++ /dev/null
@@ -1,166 +0,0 @@
-// Function.
-import { isObjectKey } from '../lib/is-object-key.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.objectKey.describe,
-  tests.is.objectKey.it
-);
-/**
- * Tests.
- */
-testing.describe(isObjectKey.name , () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isObjectKey).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isObjectKey(TESTING_CLASS, 'firstName', (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_CLASS);
-              expect(payload.key).toEqual('firstName');
-            }
-            return result;
-          });
-        })
-        // ... instance.
-        .describe(`instance`, () => {
-          testing
-            .describe(`TESTING_CLASS`, () => {
-              testing
-                // number.
-                .it('has number key', () => {
-                  expect(isObjectKey(TESTING_CLASS, 1030405027)).toBeTrue();
-                  expect(isObjectKey(TESTING_CLASS, 5)).toBeTrue();
-                })
-                // It doesn't find getter number
-                .it('has not find getter number', () => expect(isObjectKey(TESTING_CLASS, TESTING_NUMBER)).toBeFalse())
-                // string.
-                .it('has string key', () => {
-                  expect(isObjectKey(TESTING_CLASS, 'surname')).toBeTrue();
-                })
-                // symbol.
-                .it('has not find getter symbol key', () => {
-                  // It does not find getter symbol key in class
-                  expect(isObjectKey(TESTING_CLASS, TESTING_SYMBOL_NUMBER)).toBeFalse();
-                  expect(isObjectKey(TESTING_CLASS, TESTING_SYMBOL_STRING)).toBeFalse();
-                });
-            });
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isObjectKey(TESTING_FUNCTION, 'function')).toBeFalse())
-            .it(`TESTING_CLASS`, () => expect(isObjectKey(TestingClass, 'function')).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .describe(`TESTING_OBJECT`, () => {
-              testing
-                // number.
-                .it('has number key', () => {
-                  expect(isObjectKey(TESTING_OBJECT, 1030405027)).toBeTrue();
-                  expect(isObjectKey(TESTING_OBJECT, 5)).toBeTrue();
-                  expect(isObjectKey(TESTING_OBJECT, TESTING_NUMBER)).toBeTrue(); // It doesn't find getter
-                })
-                // string.
-                .it('has string key', () => {
-                  expect(isObjectKey(TESTING_OBJECT, 'key as string')).toBeTrue();
-                  expect(isObjectKey(TESTING_OBJECT, 'x')).toBeTrue();
-                  expect(isObjectKey(TESTING_OBJECT, TESTING_STRING)).toBeTrue();
-                })
-                // symbol.
-                .it('has symbol key', () => {
-                  expect(isObjectKey(TESTING_OBJECT, TESTING_SYMBOL_NUMBER)).toBeTrue();
-                  expect(isObjectKey(TESTING_OBJECT, TESTING_SYMBOL_STRING)).toBeTrue();
-                });
-            });
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => it(`${TESTING_BIGINT}`, () => expect(isObjectKey(TESTING_BIGINT, 'bigint')).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isObjectKey(TESTING_TRUE, 'boolean')).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isObjectKey(TESTING_FALSE, 'boolean')).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isObjectKey(TESTING_NULL, 'null')).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isObjectKey(TESTING_NUMBER, 'number')).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isObjectKey(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isObjectKey(TESTING_STRING, 'string')).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isObjectKey(TESTING_STRING_INSTANCE, 'string')).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isObjectKey(TESTING_SYMBOL_NUMBER, 'symbol')).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isObjectKey(TESTING_SYMBOL_STRING, 'symbol')).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isObjectKey(TESTING_UNDEFINED, 'undefined')).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () =>
-                  testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKey(TESTING_BIGINT, 'bigint')).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isObjectKey(TESTING_TRUE_INSTANCE, 'boolean')).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isObjectKey(TESTING_FALSE_INSTANCE, 'boolean')).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isObjectKey(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isObjectKey(TESTING_STRING_INSTANCE, 'string')).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-object-keys-in.spec.ts b/src/is/test/is-object-keys-in.spec.ts
deleted file mode 100644
index aea4a146..00000000
--- a/src/is/test/is-object-keys-in.spec.ts
+++ /dev/null
@@ -1,173 +0,0 @@
-// Function.
-import { isObjectKeysIn } from '../lib/is-object-keys-in.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.objectKeysIn.describe,
-  tests.is.objectKeysIn.it
-);
-/**
- * Tests.
- */
-testing.describe(isObjectKeysIn.name , () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isObjectKeysIn).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isObjectKeysIn(TESTING_CLASS, ['firstName', 'surname'], (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_CLASS);
-            }
-            return result;
-          });
-        })
-        // ... instance.
-        .describe(`instance`, () => testing
-          .describe(`TESTING_CLASS`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectKeysIn(TESTING_CLASS, [1030405027])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_CLASS, [5])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_CLASS, [TESTING_NUMBER])).toBeTrue(); // It does find getter number
-              expect(isObjectKeysIn(TESTING_CLASS, [5, 1030405027])).toBeTrue();
-            })
-            // string.
-            .it('has string key', () => {
-              expect(isObjectKeysIn(TESTING_CLASS, ['surname'])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_CLASS, ['firstName', 'surname'])).toBeTrue();
-            })
-            // symbol.
-            .it('has getter symbol key', () => {
-              // It does find getter symbol key
-              expect(isObjectKeysIn(TESTING_CLASS, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_CLASS, [TESTING_SYMBOL_STRING])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_CLASS, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-            })
-            // mixed.
-            .it('has string and number key', () => expect(isObjectKeysIn(TESTING_CLASS, [1030405027, 'firstName', 'surname'])).toBeTrue())
-          )
-        )
-        // ... function.
-        .describe(`function`, () => testing
-          .it(`TESTING_FUNCTION`, () => expect(isObjectKeysIn(TESTING_FUNCTION, ['function'])).toBeFalse())
-          .it(`TESTING_CLASS`, () => expect(isObjectKeysIn(TestingClass, ['function'])).toBeFalse())
-        )
-        // ... objects.
-        .describe('object', () => testing
-          .describe(`TESTING_OBJECT`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectKeysIn(TESTING_OBJECT, [1030405027])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, [5])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue(); // It doesn't find getter
-              expect(isObjectKeysIn(TESTING_OBJECT, [5, 1030405027])).toBeTrue();
-            })
-            // string.
-            .it('has string key', () => {
-              expect(isObjectKeysIn(TESTING_OBJECT, ['key as string'])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, ['x'])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, [TESTING_STRING])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, ['key as string', 'x', TESTING_STRING])).toBeTrue();
-            })
-            // symbol.
-            .it('has symbol key', () => {
-              expect(isObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-              expect(isObjectKeysIn(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-            })
-            // mixed.
-            .it('has mixed key', () => {
-              expect(isObjectKeysIn(TESTING_OBJECT, [
-                'key as string',
-                'x',
-                1030405027,
-                5,
-                TESTING_NUMBER,
-                TESTING_STRING,
-                TESTING_SYMBOL_NUMBER,
-                TESTING_SYMBOL_STRING,
-              ])).toBeTrue();
-            })
-          )
-        )
-        // ... primitives.
-        .describe(`primitive`, () => testing
-          // bigint
-          .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKeysIn(TESTING_BIGINT, ['bigint'])).toBeFalse()))
-          // boolean
-          .describe(`boolean`, () => testing
-            .it(`${TESTING_TRUE}`, () => expect(isObjectKeysIn(TESTING_TRUE, ['boolean'])).toBeFalse())
-            .it(`${TESTING_FALSE}`, () => expect(isObjectKeysIn(TESTING_FALSE, ['boolean'])).toBeFalse())
-          )
-          // null
-          .it(`${TESTING_NULL}`, () => expect(isObjectKeysIn(TESTING_NULL, ['null'])).toBeFalse())
-          // number
-          .describe(`number`, () => testing
-            .it(`${TESTING_NUMBER}`, () => expect(isObjectKeysIn(TESTING_NUMBER, ['number'])).toBeFalse())
-            .it(`Number(${TESTING_NUMBER})`, () => expect(isObjectKeysIn(TESTING_NUMBER_INSTANCE, ['number'])).toBeFalse())
-          )
-          // string
-          .describe(`string`, () => testing
-            .it(`${TESTING_STRING}`, () => expect(isObjectKeysIn(TESTING_STRING, ['string'])).toBeFalse())
-            .it(`String(${TESTING_STRING})`, () => expect(isObjectKeysIn(TESTING_STRING_INSTANCE, ['string'])).toBeFalse())
-          )
-          // symbol
-          .describe(`symbol`, () => testing
-            .it(`Symbol(${TESTING_NUMBER})`, () => expect(isObjectKeysIn(TESTING_SYMBOL_NUMBER, ['symbol'])).toBeFalse())
-            .it(`Symbol(${TESTING_STRING})`, () => expect(isObjectKeysIn(TESTING_SYMBOL_STRING, ['symbol'])).toBeFalse())
-          )
-          // undefined
-          .it(`${TESTING_UNDEFINED}`, () => expect(isObjectKeysIn(TESTING_UNDEFINED, ['undefined'])).toBeFalse())
-          // ... object.
-          .describe(`object`, () => testing
-            // BigInt
-            .describe(`BigInt`, () =>
-              testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKeysIn(TESTING_BIGINT, ['bigint'])).toBeFalse()))
-            // Boolean
-            .describe(`Boolean`, () => testing
-              .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isObjectKeysIn(TESTING_TRUE_INSTANCE, ['boolean'])).toBeFalse())
-              .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isObjectKeysIn(TESTING_FALSE_INSTANCE, ['boolean'])).toBeFalse())
-            )
-            // Number
-            .describe(`Number`, () =>
-              testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isObjectKeysIn(TESTING_NUMBER_INSTANCE, ['number'])).toBeFalse()))
-            // String
-            .describe(`String`, () =>
-              testing.it(`new String(${TESTING_STRING})`, () => expect(isObjectKeysIn(TESTING_STRING_INSTANCE, ['string'])).toBeFalse()))
-          )
-        );
-    });
-});
diff --git a/src/is/test/is-object-keys.spec.ts b/src/is/test/is-object-keys.spec.ts
deleted file mode 100644
index ff1bbfab..00000000
--- a/src/is/test/is-object-keys.spec.ts
+++ /dev/null
@@ -1,172 +0,0 @@
-// Function.
-import { isObjectKeys } from '../lib/is-object-keys.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.objectKeys.describe,
-  tests.is.objectKeys.it
-);
-/**
- * Tests.
- */
-testing.describe(isObjectKeys.name , () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isObjectKeys).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        // ... instance.
-        .describe(`instance`, () => testing
-          .describe(`TESTING_CLASS`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectKeys(TESTING_CLASS, [1030405027])).toBeTrue();
-              expect(isObjectKeys(TESTING_CLASS, [5])).toBeTrue();
-              expect(isObjectKeys(TESTING_CLASS, [5, 1030405027])).toBeTrue();
-            })
-            // It doesn't find getter number
-            .it('has not find getter number', () => expect(isObjectKeys(TESTING_CLASS, [TESTING_NUMBER])).toBeFalse())
-            // string.
-            .it('has string key', () => {
-              expect(isObjectKeys(TESTING_CLASS, ['surname'])).toBeTrue();
-              expect(isObjectKeys(TESTING_CLASS, ['firstName', 'surname'])).toBeTrue();
-            })
-            // symbol.
-            .it('has not find getter symbol key', () => {
-              // It does not find getter symbol key in class
-              expect(isObjectKeys(TESTING_CLASS, [TESTING_SYMBOL_NUMBER])).toBeFalse();
-              expect(isObjectKeys(TESTING_CLASS, [TESTING_SYMBOL_STRING])).toBeFalse();
-              expect(isObjectKeys(TESTING_CLASS, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeFalse();
-            })
-            // mixed.
-            .it('has string and number key', () => expect(isObjectKeys(TESTING_CLASS, [1030405027, 'firstName', 'surname'])).toBeTrue())
-          )
-        )
-        // ... function.
-        .describe(`function`, () => testing
-          .it(`TESTING_FUNCTION`, () => expect(isObjectKeys(TESTING_FUNCTION, ['function'])).toBeFalse())
-          .it(`TESTING_CLASS`, () => expect(isObjectKeys(TestingClass, ['function'])).toBeFalse())
-        )
-        // ... objects.
-        .describe('object', () => {
-          describe(`TESTING_OBJECT`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectKeys(TESTING_OBJECT, [1030405027])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, [5])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue(); // It doesn't find getter
-              expect(isObjectKeys(TESTING_OBJECT, [5, 1030405027])).toBeTrue();
-            })
-            // string.
-            .it('has string key', () => {
-              expect(isObjectKeys(TESTING_OBJECT, ['key as string'])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, ['x'])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_STRING])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, ['key as string', 'x', TESTING_STRING])).toBeTrue();
-            })
-            // symbol.
-            .it('has symbol key', () => {
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-            })
-            // mixed.
-            .it('has mixed key', () => {
-              expect(isObjectKeys(TESTING_OBJECT, [
-                'key as string',
-                'x',
-                1030405027,
-                5,
-                TESTING_NUMBER,
-                TESTING_STRING,
-                TESTING_SYMBOL_NUMBER,
-                TESTING_SYMBOL_STRING,
-              ])).toBeTrue();
-              // TRUE, TRUE
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-              // TRUE AND FALSE
-              expect(isObjectKeys(TESTING_OBJECT, [TESTING_STRING, 'no property'])).toBeFalse();
-              // FALSE AND FALSE
-              expect(isObjectKeys(TESTING_OBJECT, ['no property one', 'no property two'])).toBeFalse();
-            })
-          );
-        })
-        // ... primitives.
-        .describe(`primitive`, () => testing
-          // bigint
-          .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKeys(TESTING_BIGINT, ['bigint'])).toBeFalse()))
-          // boolean
-          .describe(`boolean`, () => testing
-            .it(`${TESTING_TRUE}`, () => expect(isObjectKeys(TESTING_TRUE, ['boolean'])).toBeFalse())
-            .it(`${TESTING_FALSE}`, () => expect(isObjectKeys(TESTING_FALSE, ['boolean'])).toBeFalse())
-          )
-          // null
-          .it(`${TESTING_NULL}`, () => expect(isObjectKeys(TESTING_NULL, ['null'])).toBeFalse())
-          // number
-          .describe(`number`, () => testing
-            .it(`${TESTING_NUMBER}`, () => expect(isObjectKeys(TESTING_NUMBER, ['number'])).toBeFalse())
-            .it(`Number(${TESTING_NUMBER})`, () => expect(isObjectKeys(TESTING_NUMBER_INSTANCE, ['number'])).toBeFalse())
-          )
-          // string
-          .describe(`string`, () => testing
-            .it(`${TESTING_STRING}`, () => expect(isObjectKeys(TESTING_STRING, ['string'])).toBeFalse())
-            .it(`String(${TESTING_STRING})`, () => expect(isObjectKeys(TESTING_STRING_INSTANCE, ['string'])).toBeFalse())
-          )
-          // symbol
-          .describe(`symbol`, () => testing
-            .it(`Symbol(${TESTING_NUMBER})`, () => expect(isObjectKeys(TESTING_SYMBOL_NUMBER, ['symbol'])).toBeFalse())
-            .it(`Symbol(${TESTING_STRING})`, () => expect(isObjectKeys(TESTING_SYMBOL_STRING, ['symbol'])).toBeFalse())
-          )
-          // undefined
-          .it(`${TESTING_UNDEFINED}`, () => expect(isObjectKeys(TESTING_UNDEFINED, ['undefined'])).toBeFalse())
-          // ... object.
-          .describe(`object`, () => testing
-            // BigInt
-            .describe(`BigInt`, () =>
-              testing.it(`${TESTING_BIGINT}`, () => expect(isObjectKeys(TESTING_BIGINT, ['bigint'])).toBeFalse()))
-            // Boolean
-            .describe(`Boolean`, () => testing
-              .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isObjectKeys(TESTING_TRUE_INSTANCE, ['boolean'])).toBeFalse())
-              .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isObjectKeys(TESTING_FALSE_INSTANCE, ['boolean'])).toBeFalse())
-            )
-            // Number
-            .describe(`Number`, () =>
-              testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isObjectKeys(TESTING_NUMBER_INSTANCE, ['number'])).toBeFalse()))
-            // String
-            .describe(`String`, () =>
-              testing.it(`new String(${TESTING_STRING})`, () => expect(isObjectKeys(TESTING_STRING_INSTANCE, ['string'])).toBeFalse()))
-          )
-        );
-    });
-});
diff --git a/src/is/test/is-object-some-keys.spec.ts b/src/is/test/is-object-some-keys.spec.ts
deleted file mode 100644
index 0fa47035..00000000
--- a/src/is/test/is-object-some-keys.spec.ts
+++ /dev/null
@@ -1,191 +0,0 @@
-// Function.
-import { isObjectSomeKeys } from '../lib/is-object-some-keys.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.objectSomeKeys.describe,
-  tests.is.objectSomeKeys.it
-);
-/**
- * Tests.
- */
-testing.describe(isObjectSomeKeys.name , () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isObjectSomeKeys).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        // ... instance.
-        .describe(`instance`, () => testing
-          .describe(`TESTING_CLASS`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectSomeKeys(TESTING_CLASS, [1030405027])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_CLASS, [5])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_CLASS, [5, 1030405027])).toBeTrue();
-            })
-            // It doesn't find getter number
-            .it('has not find getter number', () => expect(isObjectSomeKeys(TESTING_CLASS, [TESTING_NUMBER])).toBeFalse())
-            // string.
-            .it('has string key', () => {
-              expect(isObjectSomeKeys(TESTING_CLASS, ['surname'])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_CLASS, ['firstName', 'surname'])).toBeTrue();
-            })
-            // symbol.
-            .it('has not find getter symbol key', () => {
-              // It does not find getter symbol key in class
-              expect(isObjectSomeKeys(TESTING_CLASS, [TESTING_SYMBOL_NUMBER])).toBeFalse();
-              expect(isObjectSomeKeys(TESTING_CLASS, [TESTING_SYMBOL_STRING])).toBeFalse();
-              expect(isObjectSomeKeys(TESTING_CLASS, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeFalse();
-            })
-            // mixed.
-            .it('has string and number key', () => expect(isObjectSomeKeys(TESTING_CLASS, [1030405027, 'firstName', 'surname'])).toBeTrue())
-          )
-        )
-        // ... function.
-        .describe(`function`, () => testing
-          .it(`TESTING_FUNCTION`, () => expect(isObjectSomeKeys(TESTING_FUNCTION, ['function'])).toBeFalse())
-          .it(`TESTING_CLASS`, () => expect(isObjectSomeKeys(TestingClass, ['function'])).toBeFalse())
-        )
-        // ... objects.
-        .describe('object', () => {
-          describe(`TESTING_OBJECT`, () => testing
-            // number.
-            .it('has number key', () => {
-              expect(isObjectSomeKeys(TESTING_OBJECT, [1030405027])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, [5])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_NUMBER])).toBeTrue(); // It doesn't find getter
-              expect(isObjectSomeKeys(TESTING_OBJECT, [5, 1030405027])).toBeTrue();
-            })
-            // string.
-            .it('has string key', () => {
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['key as string'])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['x'])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_STRING])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['key as string', 'x', TESTING_STRING])).toBeTrue();
-            })
-            // symbol.
-            .it('has symbol key', () => {
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_STRING])).toBeTrue();
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-            })
-            // mixed.
-            .it('has mixed key', () => {
-              expect(isObjectSomeKeys(TESTING_OBJECT, [
-                'key as string',
-                'x',
-                1030405027,
-                5,
-                TESTING_NUMBER,
-                TESTING_STRING,
-                TESTING_SYMBOL_NUMBER,
-                TESTING_SYMBOL_STRING,
-              ])).toBeTrue();
-              // TRUE, TRUE
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_SYMBOL_NUMBER, TESTING_SYMBOL_STRING])).toBeTrue();
-              // [TRUE, TRUE] OR [TRUE, TRUE]
-              expect(isObjectSomeKeys(TESTING_OBJECT,
-                  [[TESTING_SYMBOL_NUMBER, TESTING_STRING], [TESTING_SYMBOL_STRING, TESTING_NUMBER]])).toBeTrue();
-              // TRUE OR FALSE
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_STRING, 'no property'])).toBeTrue();
-              // FALSE OR TRUE
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['no property', TESTING_NUMBER])).toBeTrue();
-              // [FALSE] OR [FALSE]
-              expect(isObjectSomeKeys(TESTING_OBJECT, [['no property'], ['no property']])).toBeFalse();
-              // FALSE OR FALSE
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['no property one', 'no property two'])).toBeFalse();
-              // [FALSE] OR FALSE
-              expect(isObjectSomeKeys(TESTING_OBJECT, [['no property one'], 'no property two'])).toBeFalse();
-              // FALSE OR [FALSE]
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['no property one', ['no property two']])).toBeFalse();
-              // FALSE OR [FALSE, TRUE]
-              expect(isObjectSomeKeys(TESTING_OBJECT, ['no property one', ['no property two', TESTING_STRING]])).toBeFalse();
-              // [FALSE, TRUE] OR FALSE
-              expect(isObjectSomeKeys(TESTING_OBJECT, [['no property one', TESTING_STRING], 'no property two'])).toBeFalse();
-              // TRUE OR [FALSE, TRUE]
-              expect(isObjectSomeKeys(TESTING_OBJECT, [TESTING_NUMBER, ['no property two', TESTING_STRING]])).toBeTrue();
-              // [FALSE, TRUE] OR TRUE
-              expect(isObjectSomeKeys(TESTING_OBJECT, [['no property one', TESTING_STRING], TESTING_NUMBER])).toBeTrue();
-            })
-          );
-        })
-        // ... primitives.
-        .describe(`primitive`, () => testing
-          // bigint
-          .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isObjectSomeKeys(TESTING_BIGINT, ['bigint'])).toBeFalse()))
-          // boolean
-          .describe(`boolean`, () => testing
-            .it(`${TESTING_TRUE}`, () => expect(isObjectSomeKeys(TESTING_TRUE, ['boolean'])).toBeFalse())
-            .it(`${TESTING_FALSE}`, () => expect(isObjectSomeKeys(TESTING_FALSE, ['boolean'])).toBeFalse())
-          )
-          // null
-          .it(`${TESTING_NULL}`, () => expect(isObjectSomeKeys(TESTING_NULL, ['null'])).toBeFalse())
-          // number
-          .describe(`number`, () => testing
-            .it(`${TESTING_NUMBER}`, () => expect(isObjectSomeKeys(TESTING_NUMBER, ['number'])).toBeFalse())
-            .it(`Number(${TESTING_NUMBER})`, () => expect(isObjectSomeKeys(TESTING_NUMBER_INSTANCE, ['number'])).toBeFalse())
-          )
-          // string
-          .describe(`string`, () => testing
-            .it(`${TESTING_STRING}`, () => expect(isObjectSomeKeys(TESTING_STRING, ['string'])).toBeFalse())
-            .it(`String(${TESTING_STRING})`, () => expect(isObjectSomeKeys(TESTING_STRING_INSTANCE, ['string'])).toBeFalse())
-          )
-          // symbol
-          .describe(`symbol`, () => testing
-            .it(`Symbol(${TESTING_NUMBER})`, () => expect(isObjectSomeKeys(TESTING_SYMBOL_NUMBER, ['symbol'])).toBeFalse())
-            .it(`Symbol(${TESTING_STRING})`, () => expect(isObjectSomeKeys(TESTING_SYMBOL_STRING, ['symbol'])).toBeFalse())
-          )
-          // undefined
-          .it(`${TESTING_UNDEFINED}`, () => expect(isObjectSomeKeys(TESTING_UNDEFINED, ['undefined'])).toBeFalse())
-          // ... object.
-          .describe(`object`, () => testing
-            // BigInt
-            .describe(`BigInt`, () =>
-              testing.it(`${TESTING_BIGINT}`, () => expect(isObjectSomeKeys(TESTING_BIGINT, ['bigint'])).toBeFalse()))
-            // Boolean
-            .describe(`Boolean`, () => testing
-              .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isObjectSomeKeys(TESTING_TRUE_INSTANCE, ['boolean'])).toBeFalse())
-              .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isObjectSomeKeys(TESTING_FALSE_INSTANCE, ['boolean'])).toBeFalse())
-            )
-            // Number
-            .describe(`Number`, () =>
-              testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isObjectSomeKeys(TESTING_NUMBER_INSTANCE, ['number'])).toBeFalse()))
-            // String
-            .describe(`String`, () =>
-              testing.it(`new String(${TESTING_STRING})`, () => expect(isObjectSomeKeys(TESTING_STRING_INSTANCE, ['string'])).toBeFalse()))
-          )
-        );
-    });
-});
diff --git a/src/is/test/is-object.spec.ts b/src/is/test/is-object.spec.ts
deleted file mode 100644
index a898d36d..00000000
--- a/src/is/test/is-object.spec.ts
+++ /dev/null
@@ -1,134 +0,0 @@
-// Function.
-import { isObject } from '../lib/is-object.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.object.describe,
-  tests.is.object.it
-);
-/**
- * Checks
- * ✓ typeof === 'object'
- * ✓ instanceof Object
- */
-testing.describe(isObject.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isObject).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isObject(TESTING_OBJECT, (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_OBJECT);
-            }
-            return result;
-          });
-        })
-
-        // ... arrays.
-        .describe(`array`, () => {})
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isObject(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isObject(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isObject(TESTING_CLASS)).toBeTrue())
-            .it(`TESTING_OBJECT`, () => expect(isObject(TESTING_OBJECT)).toBeTrue())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isObject(TESTING_OBJECT)).toBeTrue())
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isObject(TESTING_BIGINT)).toBeFalse()))
-
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isObject(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isObject(TESTING_FALSE)).toBeFalse());
-            })
-
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isObject(TESTING_NULL)).toBeFalse())
-
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isObject(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isObject(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isObject(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isObject(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isObject(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isObject(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isObject(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isObject(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isObject(TESTING_TRUE_INSTANCE)).toBeTrue())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isObject(TESTING_FALSE_INSTANCE)).toBeTrue());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isObject(TESTING_NUMBER_INSTANCE)).toBeTrue()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isObject(TESTING_STRING_INSTANCE)).toBeTrue()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-param.spec.ts b/src/is/test/is-param.spec.ts
deleted file mode 100644
index a0022f37..00000000
--- a/src/is/test/is-param.spec.ts
+++ /dev/null
@@ -1,73 +0,0 @@
-// Decorator.
-import { isParam } from '../lib/is-param.decorator';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_NUMBER,
-  TESTING_STRING,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-
-class TestClass {
-  @isParam('object', 'string', 'number')
-  public testMethod(object?: any, firstName?: any, age?: any): { object: any, firstName: any, age: any } {
-    return {object, firstName, age};
-  }
-}
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.param.describe,
-  tests.is.param.it
-);
-/**
- * Tests.
- */
-testing.describe(isParam.name, () => {
-  const resultTRUE = new TestClass().testMethod({firstName: 'NoName'}, TESTING_STRING, TESTING_NUMBER);
-  const resultFALSE = new TestClass().testMethod(TESTING_NUMBER, {firstName: 'NoName'}, TESTING_STRING);
-
-  testing
-  // Defined.
-  .it('is DEFINED', () => expect(isParam).toBeDefined())
-
-  // Checks ...
-  .describe(`checks`, () => {
-    testing
-    // ... objects.
-    .describe('object', () => {
-      testing
-      .it(`TESTING_CLASS`, () => {
-        expect(resultTRUE.object).toEqual({firstName: 'NoName'});
-        expect(resultFALSE.object).toBeUndefined();
-      });
-    })
-
-    // ... primitives.
-    .describe(`primitive`, () => {
-      testing
-      // number
-      .describe(`number`, () => {
-        testing
-        .it(`${TESTING_NUMBER}`, () => {
-          expect(resultTRUE.age).toBe(TESTING_NUMBER);
-          expect(resultFALSE.age).toBeUndefined();
-        });
-      })
-
-      // string
-      .describe(`string`, () => {
-        testing
-        .it(`${TESTING_STRING}`, () => {
-          expect(resultTRUE.firstName).toBe(TESTING_STRING);
-          expect(resultFALSE.firstName).toBeUndefined();
-        });
-      });
-    });
-  });
-});
diff --git a/src/is/test/is-primitive.spec.ts b/src/is/test/is-primitive.spec.ts
deleted file mode 100644
index 802d2658..00000000
--- a/src/is/test/is-primitive.spec.ts
+++ /dev/null
@@ -1,111 +0,0 @@
-// Function.
-import { isPrimitive } from '../lib/is-primitive.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.primitive.describe,
-  tests.is.primitive.it
-);
-/**
- * Tests.
- */
-testing.describe(isPrimitive.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isPrimitive).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isPrimitive<string>(TESTING_STRING, 'string' , (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isPrimitive(TESTING_BIGINT, 'bigint')).toBeTrue()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isPrimitive(TESTING_TRUE, 'boolean')).toBeTrue())
-                .it(`${TESTING_FALSE}`, () => expect(isPrimitive(TESTING_FALSE, 'boolean')).toBeTrue());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isPrimitive(TESTING_NULL, 'null')).toBeTrue())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isPrimitive(TESTING_NUMBER, 'number')).toBeTrue())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isPrimitive(TESTING_NUMBER_CONSTRUCTOR, 'number')).toBeTrue());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isPrimitive(TESTING_STRING, 'string')).toBeTrue())
-                .it(`String(${TESTING_STRING})`, () => expect(isPrimitive(TESTING_STRING_CONSTRUCTOR, 'string')).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isPrimitive(TESTING_SYMBOL_NUMBER, 'symbol')).toBeTrue())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isPrimitive(TESTING_SYMBOL_STRING, 'symbol')).toBeTrue());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isPrimitive(TESTING_UNDEFINED, 'undefined')).toBeTrue())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () =>
-                  testing.it(`${TESTING_BIGINT}`, () => expect(isPrimitive(TESTING_BIGINT, 'bigint')).toBeTrue()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isPrimitive(TESTING_TRUE_INSTANCE, 'boolean')).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isPrimitive(TESTING_FALSE_INSTANCE, 'boolean')).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isPrimitive(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isPrimitive(TESTING_STRING_INSTANCE, 'string')).toBeFalse()));
-            });
-
-        });
-    });
-});
diff --git a/src/is/test/is-regexp.spec.ts b/src/is/test/is-regexp.spec.ts
deleted file mode 100644
index 128beee3..00000000
--- a/src/is/test/is-regexp.spec.ts
+++ /dev/null
@@ -1,133 +0,0 @@
-// Function.
-import { isRegExp } from '../lib/is-regexp.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_REGEXP,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.regexp.describe,
-  tests.is.regexp.it
-);
-/**
- * Tests.
- */
-testing.describe(isRegExp.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isRegExp).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing.
-        it('callback', () => {
-          isRegExp(TESTING_REGEXP, (result: boolean) => {
-            expect(result).toBeTrue();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => {})
-        // ... Date.
-        .describe(`date`, () => {
-          testing
-            .it(`TESTING_DATE`, () => expect(isRegExp(TESTING_DATE)).toBeFalse())
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isRegExp(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isRegExp(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isRegExp(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isRegExp(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isRegExp(TESTING_OBJECT)).toBeFalse())
-            .it(`TESTING_REGEXP ${TESTING_REGEXP}`, () => expect(isRegExp(TESTING_REGEXP)).toBeTrue());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isRegExp(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isRegExp(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isRegExp(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isRegExp(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isRegExp(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isRegExp(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isRegExp(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isRegExp(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isRegExp(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isRegExp(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isRegExp(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isRegExp(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isRegExp(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isRegExp(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isRegExp(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isRegExp(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string-includes-some.spec.ts b/src/is/test/is-string-includes-some.spec.ts
deleted file mode 100644
index 147e9e18..00000000
--- a/src/is/test/is-string-includes-some.spec.ts
+++ /dev/null
@@ -1,190 +0,0 @@
-// Function.
-import { isStringIncludesSome } from '../lib/is-string-includes-some.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringIncludesSome.describe,
-  tests.is.stringIncludesSome.it
-);
-/**
- * Tests.
- */
-testing.describe(isStringIncludesSome.name, () => {
-  const TESTING_STRING_LONG = `Lorem Ipsum is simply dummy text of the printing and typesetting industry.
-  Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,
-  when an unknown printer took a galley of type and scrambled it to make a type specimen book.
-  It has survived not only five centuries, but also the leap into electronic typesetting,
-  remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset
-  sheets containing Lorem Ipsum passages, and more recently with desktop publishing software
-  like Aldus PageMaker including versions of Lorem Ipsum.`;
-
-  const TESTING_STRING_LONG_INSTANCE = new String(TESTING_STRING_LONG);
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isStringIncludesSome).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isStringIncludesSome(TESTING_STRING, ['Company'], (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isStringIncludesSome(TESTING_FUNCTION, ['1', '2', '3'])).toBeFalse())
-            .it(`TestingClass`, () => expect(isStringIncludesSome(TestingClass, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isStringIncludesSome(TESTING_CLASS, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isStringIncludesSome(TESTING_OBJECT, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () =>
-              testing.it(`${TESTING_BIGINT}`, () =>
-                  expect(isStringIncludesSome(TESTING_BIGINT, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isStringIncludesSome(TESTING_TRUE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isStringIncludesSome(TESTING_FALSE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isStringIncludesSome(TESTING_NULL, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () =>
-                  expect(isStringIncludesSome(TESTING_NUMBER, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () =>
-                  expect(isStringIncludesSome(TESTING_NUMBER_INSTANCE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`TESTING_STRING, TESTING_STRING_LONG`, () => {
-                  expect(isStringIncludesSome(TESTING_STRING, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeTrue();
-                    // No word exists.
-                  expect(isStringIncludesSome(TESTING_STRING_LONG, [
-                    'no text',
-                    'no text is here'
-                  ])).toBeFalse();
-
-                  // Every word exists.
-                  expect(isStringIncludesSome(TESTING_STRING_LONG, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                  ])).toBeTrue();
-
-                  // Some word exists.
-                  expect(isStringIncludesSome(TESTING_STRING_LONG, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                    'no text is here'
-                  ])).toBeTrue();
-                })
-                .it(`String(${TESTING_STRING})`, () =>
-                  expect(isStringIncludesSome(TESTING_STRING_CONSTRUCTOR, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isStringIncludesSome(TESTING_SYMBOL_NUMBER, [])).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isStringIncludesSome(TESTING_SYMBOL_STRING, [])).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () =>
-              expect(isStringIncludesSome(TESTING_UNDEFINED, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () =>
-                      expect(isStringIncludesSome(TESTING_TRUE_INSTANCE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () =>
-                      expect(isStringIncludesSome(TESTING_FALSE_INSTANCE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () =>
-                    expect(isStringIncludesSome(TESTING_NUMBER_INSTANCE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => {
-                    expect(isStringIncludesSome(TESTING_STRING_INSTANCE, [TESTING_STRING, '!@#$%^&*()', '3'])).toBeTrue();
-
-                    // No word exists.
-                    expect(isStringIncludesSome(TESTING_STRING_LONG_INSTANCE, [
-                      'no text',
-                      'no text is here'
-                    ])).toBeFalse();
-
-                    // Every word exists.
-                    expect(isStringIncludesSome(TESTING_STRING_LONG_INSTANCE, [
-                      'Lorem',
-                      'unchanged',
-                      'versions',
-                      'only',
-                    ])).toBeTrue();
-
-                    // Some word exists.
-                    expect(isStringIncludesSome(TESTING_STRING_LONG_INSTANCE, [
-                      'Lorem',
-                      'unchanged',
-                      'versions',
-                      'only',
-                      'no text is here'
-                    ])).toBeTrue();
-                  }));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string-includes.spec.ts b/src/is/test/is-string-includes.spec.ts
deleted file mode 100644
index 2716cff7..00000000
--- a/src/is/test/is-string-includes.spec.ts
+++ /dev/null
@@ -1,190 +0,0 @@
-// Function.
-import { isStringIncludes } from '../lib/is-string-includes.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringIncludes.describe,
-  tests.is.stringIncludes.it
-);
-/**
- * Tests.
- */
-testing.describe(isStringIncludes.name, () => {
-  const TESTING_STRING_LONG = `Lorem Ipsum is simply dummy text of the printing and typesetting industry.
-  Lorem Ipsum has been the industry's standard dummy text ever since the 1500s,
-  when an unknown printer took a galley of type and scrambled it to make a type specimen book.
-  It has survived not only five centuries, but also the leap into electronic typesetting,
-  remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset
-  sheets containing Lorem Ipsum passages, and more recently with desktop publishing software
-  like Aldus PageMaker including versions of Lorem Ipsum.`;
-
-  const TESTING_STRING_LONG_INSTANCE = new String(TESTING_STRING_LONG);
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isStringIncludes).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isStringIncludes(TESTING_STRING, ['Company'], (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isStringIncludes(TESTING_FUNCTION, [])).toBeFalse())
-            .it(`TestingClass`, () => expect(isStringIncludes(TestingClass, [])).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isStringIncludes(TESTING_CLASS, [])).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isStringIncludes(TESTING_OBJECT, [])).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isStringIncludes(TESTING_BIGINT, [])).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isStringIncludes(TESTING_TRUE, [])).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isStringIncludes(TESTING_FALSE, [])).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isStringIncludes(TESTING_NULL, [])).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isStringIncludes(TESTING_NUMBER, [])).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isStringIncludes(TESTING_NUMBER_INSTANCE, [])).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => {
-                  expect(isStringIncludes(TESTING_STRING, ['Company'])).toBeTrue();
-                  expect(isStringIncludes(TESTING_STRING, [TESTING_STRING, '!@#$%^&*()'])).toBeTrue();
-                    // No word exists.
-                  expect(isStringIncludes(TESTING_STRING_LONG, [
-                    'no text',
-                    'no text is here'
-                  ])).toBeFalse();
-
-                  // Every word exists.
-                  expect(isStringIncludes(TESTING_STRING_LONG, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                  ])).toBeTrue();
-
-                  // Some word exists.
-                  expect(isStringIncludes(TESTING_STRING_LONG, [
-                    'Lorem',
-                    'unchanged',
-                    'versions',
-                    'only',
-                    'no text is here'
-                  ])).toBeFalse();
-                })
-                .it(`String(${TESTING_STRING})`, () =>
-                  expect(isStringIncludes(TESTING_STRING_CONSTRUCTOR, [TESTING_STRING, '!@#$%^&*()'])).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () =>
-                  expect(isStringIncludes(TESTING_SYMBOL_NUMBER, ['1', '2', '123123'])).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () =>
-                  expect(isStringIncludes(TESTING_SYMBOL_STRING, ['1', '2', '123123'])).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isStringIncludes(TESTING_UNDEFINED, [ '1', '2', '123123' ])).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () =>
-                  testing.it(`${TESTING_BIGINT}`, () => expect(isStringIncludes(TESTING_BIGINT, [ '1', '2', '123123' ])).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () =>
-                      expect(isStringIncludes(TESTING_TRUE_INSTANCE, [ '1', '2', '123123' ])).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () =>
-                      expect(isStringIncludes(TESTING_FALSE_INSTANCE, [])).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isStringIncludes(TESTING_NUMBER_INSTANCE, [])).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => {
-                    expect(isStringIncludes(TESTING_STRING_INSTANCE, [])).toBeTrue();
-
-                    // No word exists.
-                    expect(isStringIncludes(TESTING_STRING_LONG, [
-                      'no text',
-                      'no text is here'
-                    ])).toBeFalse();
-
-                    // Every word exists.
-                    expect(isStringIncludes(TESTING_STRING_LONG_INSTANCE, [
-                      'Lorem',
-                      'unchanged',
-                      'versions',
-                      'only',
-                    ])).toBeTrue();
-
-                    // Some word exists.
-                    expect(isStringIncludes(TESTING_STRING_LONG_INSTANCE, [
-                      'Lorem',
-                      'unchanged',
-                      'versions',
-                      'only',
-                      'no text is here'
-                    ])).toBeFalse();
-                }));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string-length-between.spec.ts b/src/is/test/is-string-length-between.spec.ts
deleted file mode 100644
index c194db75..00000000
--- a/src/is/test/is-string-length-between.spec.ts
+++ /dev/null
@@ -1,154 +0,0 @@
-// Function.
-import { isStringLengthBetween } from '../lib/is-string-length-between.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_ARRAY_STRING,
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringLengthBetween.describe,
-  tests.is.stringLengthBetween.it
-);
-/**
- * Tests.
- */
-testing.describe(`isStringLengthBetween()`, () => {
-  // Constant.
-  const min = 0;
-  const max = 13;
-  const stringFirstName = 'my first name';
-  const stringInstance = new String(stringFirstName);
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isStringLengthBetween).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isStringLengthBetween(TESTING_FALSE, min, max, (result: boolean) => {
-            expect(result).toBeFalse();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => {
-          testing
-            .it(`TESTING_ARRAY_STRING`, () => expect(isStringLengthBetween(TESTING_ARRAY_STRING, min, max)).toBeFalse());
-        })
-        // ... Date.
-        .describe(`date`, () => {
-          testing
-            .it(`TESTING_DATE`, () => expect(isStringLengthBetween(TESTING_DATE, min, max)).toBeFalse())
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`FUNCTION ${min} ${max}`, () => expect(isStringLengthBetween(TESTING_FUNCTION, min, max)).toBeFalse())
-            .it(`TestingClass ${min} ${max}`, () => expect(isStringLengthBetween(TestingClass, min, max)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isStringLengthBetween(TESTING_CLASS, min, max)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isStringLengthBetween(TESTING_OBJECT, min, max)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => it(`${TESTING_BIGINT}`, () => expect(isStringLengthBetween(TESTING_BIGINT, min, max)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isStringLengthBetween(TESTING_TRUE, min, max)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isStringLengthBetween(TESTING_FALSE, min, max)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isStringLengthBetween(TESTING_NULL, min, max)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isStringLengthBetween(TESTING_NUMBER, min, max)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isStringLengthBetween(TESTING_NUMBER_INSTANCE, min, max)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isStringLengthBetween(TESTING_STRING, min, max)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isStringLengthBetween(TESTING_STRING_INSTANCE, min, max)).toBeFalse())
-                .it(`${stringFirstName}`, () => expect(isStringLengthBetween(stringFirstName, min, max)).toBeTrue())
-                .it(`${stringFirstName}`, () => expect(isStringLengthBetween(stringFirstName, 13, max)).toBeTrue())
-                .it(`${stringFirstName}`, () => expect(isStringLengthBetween(stringFirstName, 14, max)).toBeFalse())
-                .it(`${stringFirstName}`, () => expect(isStringLengthBetween(stringFirstName, min, 12)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isStringLengthBetween(TESTING_SYMBOL_NUMBER, min, max)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isStringLengthBetween(TESTING_SYMBOL_STRING, min, max)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isStringLengthBetween(TESTING_UNDEFINED, min, max)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt constructor`, () =>
-                  testing.it(`${TESTING_BIGINT}`, () => expect(isStringLengthBetween(BigInt(1n), min, max)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isStringLengthBetween(TESTING_TRUE_INSTANCE, min, max)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isStringLengthBetween(TESTING_FALSE_INSTANCE, min, max)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () => {
-                  testing
-                    .it(`new Number(${TESTING_NUMBER})`, () => expect(isStringLengthBetween(TESTING_NUMBER_INSTANCE, min, max)).toBeFalse())
-                    .it(`new Number(${stringFirstName})`, () => expect(isStringLengthBetween(new Number(stringFirstName), min, max)).toBeFalse())
-                    .it(`new Number(${stringFirstName})`, () => expect(isStringLengthBetween(new Number(1.15), min, max)).toBeFalse())
-                    .it(`new Number(${stringFirstName})`, () => expect(isStringLengthBetween(new Number(13.15), min, max)).toBeFalse());
-                })
-                // String
-                .describe(`String`, () => {
-                  testing
-                    .it(`new String(${TESTING_STRING})`, () => expect(isStringLengthBetween(TESTING_STRING_INSTANCE, min, max)).toBeFalse())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLengthBetween(stringInstance, min, max)).toBeTrue())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLengthBetween(stringInstance, 13, max)).toBeTrue())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLengthBetween(stringInstance, 14, max)).toBeFalse())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLengthBetween(stringInstance, min, 12)).toBeFalse());
-                });
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string-length.spec.ts b/src/is/test/is-string-length.spec.ts
deleted file mode 100644
index ee5fb13a..00000000
--- a/src/is/test/is-string-length.spec.ts
+++ /dev/null
@@ -1,153 +0,0 @@
-// Function.
-import { isStringLength } from '../lib/is-string-length.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_ARRAY_STRING,
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringLength.describe,
-  tests.is.stringLength.it
-);
-/**
- * Tests.
- */
-testing.describe(isStringLength.name, () => {
-  // Constant.
-  const length = 13;
-  const stringFirstName = 'my first name';
-  const stringInstance = new String(stringFirstName);
-
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isStringLength).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isStringLength(TESTING_FALSE, length, (result: boolean) => {
-            expect(result).toBeFalse();
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => {
-          testing
-            .it(`TESTING_ARRAY_STRING`, () => expect(isStringLength(TESTING_ARRAY_STRING, length)).toBeFalse());
-        })
-        // ... Date.
-        .describe(`date`, () => {
-          testing
-            .it(`TESTING_DATE`, () => expect(isStringLength(TESTING_DATE, length)).toBeFalse());
-        })
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`FUNCTION ${length}`, () => expect(isStringLength(TESTING_FUNCTION, length)).toBeFalse())
-            .it(`TestingClass ${length}`, () => expect(isStringLength(TestingClass, length)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isStringLength(TESTING_CLASS, length)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isStringLength(TESTING_OBJECT, length)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => it(`${TESTING_BIGINT}`, () => expect(isStringLength(TESTING_BIGINT, length)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isStringLength(TESTING_TRUE, length)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isStringLength(TESTING_FALSE, length)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isStringLength(TESTING_NULL, length)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isStringLength(TESTING_NUMBER, length)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isStringLength(TESTING_NUMBER_INSTANCE, length)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isStringLength(TESTING_STRING, length)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isStringLength(TESTING_STRING_INSTANCE, length)).toBeFalse())
-                .it(`${stringFirstName}`, () => expect(isStringLength(stringFirstName, length)).toBeTrue())
-                .it(`${stringFirstName}`, () => expect(isStringLength(stringFirstName, 13)).toBeTrue())
-                .it(`${stringFirstName}`, () => expect(isStringLength(stringFirstName, 14)).toBeFalse())
-                .it(`${stringFirstName}`, () => expect(isStringLength(stringFirstName, 12)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isStringLength(TESTING_SYMBOL_NUMBER, length)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isStringLength(TESTING_SYMBOL_STRING, length)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isStringLength(TESTING_UNDEFINED, length)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt constructor`, () =>
-                  testing.it(`${TESTING_BIGINT}`, () => expect(isStringLength(BigInt(1n), length)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isStringLength(TESTING_TRUE_INSTANCE, length)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isStringLength(TESTING_FALSE_INSTANCE, length)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () => {
-                  testing
-                    .it(`new Number(${TESTING_NUMBER})`, () => expect(isStringLength(TESTING_NUMBER_INSTANCE, length)).toBeFalse())
-                    .it(`new Number(${stringFirstName})`, () => expect(isStringLength(new Number(stringFirstName), length)).toBeFalse())
-                    .it(`new Number(${stringFirstName})`, () => expect(isStringLength(new Number(1.15), length)).toBeFalse())
-                    .it(`new Number(${stringFirstName})`, () => expect(isStringLength(new Number(13.15), length)).toBeFalse());
-                })
-                // String
-                .describe(`String`, () => {
-                  testing
-                    .it(`new String(${TESTING_STRING})`, () => expect(isStringLength(TESTING_STRING_INSTANCE, length)).toBeFalse())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLength(stringInstance, length)).toBeTrue())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLength(stringInstance, 13)).toBeTrue())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLength(stringInstance, 14)).toBeFalse())
-                    .it(`new String(${stringFirstName})`, () => expect(isStringLength(stringInstance, 12)).toBeFalse());
-                });
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string-object.spec.ts b/src/is/test/is-string-object.spec.ts
deleted file mode 100644
index ee038ece..00000000
--- a/src/is/test/is-string-object.spec.ts
+++ /dev/null
@@ -1,127 +0,0 @@
-// Function.
-import { isStringObject } from '../lib/is-string-object.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringObject.describe,
-  tests.is.stringObject.it
-);
-/**
- * Checks
- * ✓ typeof === 'object' && instanceof String === true && instanceof Object === true
- */
-testing.describe(isStringObject.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isStringObject).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isStringObject(TESTING_STRING_INSTANCE, (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING_INSTANCE);
-            }
-            return result;
-          });
-        })
-
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isStringObject(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isStringObject(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isStringObject(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isStringObject(TESTING_OBJECT)).toBeFalse())
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isStringObject(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isStringObject(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isStringObject(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isStringObject(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isStringObject(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isStringObject(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isStringObject(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isStringObject(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isStringObject(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isStringObject(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isStringObject(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isStringObject(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isStringObject(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isStringObject(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isStringObject(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isStringObject(TESTING_STRING_INSTANCE)).toBeTrue()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string-type.spec.ts b/src/is/test/is-string-type.spec.ts
deleted file mode 100644
index 61684b89..00000000
--- a/src/is/test/is-string-type.spec.ts
+++ /dev/null
@@ -1,128 +0,0 @@
-// Function.
-import { isStringType } from '../lib/is-string-type.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.stringType.describe,
-  tests.is.stringType.it
-);
-/**
- * Tests.
- */
-testing.describe(isStringType.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isStringType).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isStringType(TESTING_STRING, (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => {})
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isStringType(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isStringType(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isStringType(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isStringType(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isStringType(TESTING_OBJECT)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isStringType(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isStringType(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isStringType(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isStringType(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isStringType(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isStringType(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isStringType(TESTING_STRING)).toBeTrue())
-                .it(`String(${TESTING_STRING})`, () => expect(isStringType(TESTING_STRING_CONSTRUCTOR)).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isStringType(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isStringType(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isStringType(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isStringType(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isStringType(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isStringType(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isStringType(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isStringType(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-string.spec.ts b/src/is/test/is-string.spec.ts
deleted file mode 100644
index 9789a704..00000000
--- a/src/is/test/is-string.spec.ts
+++ /dev/null
@@ -1,128 +0,0 @@
-// Function.
-import { isString } from '../lib/is-string.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.string.describe,
-  tests.is.string.it
-);
-/**
- * Tests.
- */
-testing.describe(isString.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isString).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isString(TESTING_STRING, (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-        })
-        // ... arrays.
-        .describe(`array`, () => {})
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isString(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isString(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isString(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isString(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isString(TESTING_OBJECT)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isString(TESTING_BIGINT)).toBeFalse()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isString(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isString(TESTING_FALSE)).toBeFalse());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isString(TESTING_NULL)).toBeFalse())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isString(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isString(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isString(TESTING_STRING)).toBeTrue())
-                .it(`String(${TESTING_STRING})`, () => expect(isString(TESTING_STRING_CONSTRUCTOR)).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isString(TESTING_SYMBOL_NUMBER)).toBeFalse())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isString(TESTING_SYMBOL_STRING)).toBeFalse());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isString(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isString(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isString(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isString(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isString(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isString(TESTING_STRING_INSTANCE)).toBeTrue()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-symbol.spec.ts b/src/is/test/is-symbol.spec.ts
deleted file mode 100644
index 3375aabd..00000000
--- a/src/is/test/is-symbol.spec.ts
+++ /dev/null
@@ -1,129 +0,0 @@
-// Function.
-import { isSymbol } from '../lib/is-symbol.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.symbol.describe,
-  tests.is.symbol.it
-);
-/**
- * Tests.
- */
-testing.describe(isSymbol.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isSymbol).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isSymbol(TESTING_SYMBOL_NUMBER, (result: boolean) => {
-            expect(result).toBeTrue();
-            return result;
-          });
-        })
-
-        // ... arrays.
-        .describe(`array`, () => {})
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`TESTING_FUNCTION`, () => expect(isSymbol(TESTING_FUNCTION)).toBeFalse())
-            .it(`TestingClass`, () => expect(isSymbol(TestingClass)).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isSymbol(TESTING_CLASS)).toBeFalse())
-            .it(`TESTING_OBJECT`, () => expect(isSymbol(TESTING_OBJECT)).toBeFalse())
-            .it(`new Object(OBJECT_ONE_NEW})`, () => expect(isSymbol(TESTING_OBJECT)).toBeFalse());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isSymbol(TESTING_BIGINT)).toBeFalse()))
-
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isSymbol(TESTING_TRUE)).toBeFalse())
-                .it(`${TESTING_FALSE}`, () => expect(isSymbol(TESTING_FALSE)).toBeFalse());
-            })
-
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isSymbol(TESTING_NULL)).toBeFalse())
-
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isSymbol(TESTING_NUMBER)).toBeFalse())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isSymbol(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isSymbol(TESTING_STRING)).toBeFalse())
-                .it(`String(${TESTING_STRING})`, () => expect(isSymbol(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isSymbol(TESTING_SYMBOL_NUMBER)).toBeTrue())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isSymbol(TESTING_SYMBOL_STRING)).toBeTrue());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isSymbol(TESTING_UNDEFINED)).toBeFalse())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isSymbol(TESTING_BIGINT)).toBeFalse()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isSymbol(TESTING_TRUE_INSTANCE)).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isSymbol(TESTING_FALSE_INSTANCE)).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isSymbol(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isSymbol(TESTING_STRING_INSTANCE)).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-true.spec.ts b/src/is/test/is-true.spec.ts
deleted file mode 100644
index 574b5ded..00000000
--- a/src/is/test/is-true.spec.ts
+++ /dev/null
@@ -1,117 +0,0 @@
-// Function.
-import { isTrue } from '../lib/is-true.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_DATE,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.true.describe,
-  tests.is.true.it
-);
-/**
- * Tests.
- */
-testing.describe(isTrue.name, () => {
-  // Defined.
-  it('is DEFINED', () => expect(isTrue).toBeDefined());
-
-  // Checks ...
-  describe(`checks`, () => {
-    it('callback', () => {
-      isTrue(TESTING_TRUE, (result: boolean) => {
-        expect(result).toBeTrue();
-        return result;
-      });
-    });
-    // ... arrays.
-    describe(`array`, () => {});
-    // ... Date.
-    describe(`date`, () => {
-      it(`TESTING_DATE`, () => expect(isTrue(TESTING_DATE)).toBeFalse());
-    });
-    // ... function.
-    describe(`function`, () => {
-      it(`TESTING_FUNCTION`, () => expect(isTrue(TESTING_FUNCTION)).toBeFalse());
-      it(`TestingClass`, () => expect(isTrue(TestingClass)).toBeFalse());
-    });
-    // ... objects.
-    describe('object', () => {
-      it(`TESTING_CLASS`, () => expect(isTrue(TESTING_CLASS)).toBeFalse());
-      it(`TESTING_OBJECT`, () => expect(isTrue(TESTING_OBJECT)).toBeFalse());
-      it(`new Object(OBJECT_ONE_NEW})`, () => expect(isTrue(TESTING_OBJECT)).toBeFalse());
-    });
-    // ... primitives.
-    describe(`primitive`, () => {
-      // bigint
-      describe(`bigint`, () => it(`${TESTING_BIGINT}`, () => expect(isTrue(TESTING_BIGINT)).toBeFalse()));
-      // boolean
-      describe(`boolean`, () => {
-        it(`${TESTING_TRUE}`, () => expect(isTrue(TESTING_TRUE)).toBeTrue());
-        it(`${TESTING_FALSE}`, () => expect(isTrue(TESTING_FALSE)).toBeFalse());
-      });
-      // null
-      it(`${TESTING_NULL}`, () => expect(isTrue(TESTING_NULL)).toBeFalse());
-      // number
-      describe(`number`, () => {
-        it(`${TESTING_NUMBER}`, () => expect(isTrue(TESTING_NUMBER)).toBeFalse());
-        it(`Number(${TESTING_NUMBER})`, () => expect(isTrue(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-      });
-      // string
-      describe(`string`, () => {
-        it(`${TESTING_STRING}`, () => expect(isTrue(TESTING_STRING)).toBeFalse());
-        it(`String(${TESTING_STRING})`, () => expect(isTrue(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-      });
-      // symbol
-      describe(`symbol`, () => {
-        it(`Symbol(${TESTING_NUMBER})`, () => expect(isTrue(TESTING_SYMBOL_NUMBER)).toBeFalse());
-        it(`Symbol(${TESTING_STRING})`, () => expect(isTrue(TESTING_SYMBOL_STRING)).toBeFalse());
-      });
-      // undefined
-      it(`${TESTING_UNDEFINED}`, () => expect(isTrue(TESTING_UNDEFINED)).toBeFalse());
-      // ... object.
-      describe(`object`, () => {
-        // BigInt
-        describe(`BigInt`, () => it(`${TESTING_BIGINT}`, () => expect(isTrue(TESTING_BIGINT)).toBeFalse()));
-        // Boolean
-        describe(`Boolean`, () => {
-          it(`${TESTING_TRUE_INSTANCE}`, () => expect(isTrue(TESTING_TRUE_INSTANCE)).toBeTrue());
-          it(`${TESTING_FALSE_INSTANCE}`, () => expect(isTrue(TESTING_FALSE_INSTANCE)).toBeFalse());
-        });
-        // Number
-        describe(`Number`, () => it(`new Number(${TESTING_NUMBER})`, () => expect(isTrue(TESTING_NUMBER_INSTANCE)).toBeFalse()));
-        // String
-        describe(`String`, () => it(`new String(${TESTING_STRING})`, () => expect(isTrue(TESTING_STRING_INSTANCE)).toBeFalse()));
-      });
-    });
-  });
-});
diff --git a/src/is/test/is-type.spec.ts b/src/is/test/is-type.spec.ts
deleted file mode 100644
index 9f758ef3..00000000
--- a/src/is/test/is-type.spec.ts
+++ /dev/null
@@ -1,134 +0,0 @@
-// Function.
-import { isType } from '../lib/is-type.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.type.describe,
-  tests.is.type.it
-);
-/**
- * Tests.
- */
-testing.describe(isType.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isType).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing
-        .it('callback', () => {
-          isType(TESTING_STRING, 'string', (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_STRING);
-            }
-            return result;
-          });
-          isType(TESTING_NUMBER, 'number', (result, value, payload) => {
-            expect(result).toBeTrue();
-            if (payload) {
-              expect(value).toEqual(TESTING_NUMBER);
-            }
-            return result;
-          });
-        })
-        // ... instance.
-        .describe(`instance`, () => testing.it(`TestingClass`, () => expect(isType<TestingClass>(TESTING_CLASS, TestingClass)).toBeTrue()))
-        // ... function.
-        .describe(`function`, () => {
-          testing
-            .it(`${TESTING_FUNCTION}`, () => expect(isType(TESTING_FUNCTION, 'function')).toBeTrue())
-            .it(`${TESTING_CLASS}`, () => expect(isType(TestingClass, 'function')).toBeFalse());
-        })
-        // ... objects.
-        .describe('object', () => {
-          testing
-            .it(`TESTING_CLASS`, () => expect(isType(TESTING_CLASS, 'object')).toBeTrue())
-            .it(`TESTING_OBJECT`, () => expect(isType(TESTING_OBJECT, 'object')).toBeTrue());
-        })
-        // ... primitives.
-        .describe(`primitive`, () => {
-          testing
-            // bigint
-            .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isType(TESTING_BIGINT, 'bigint')).toBeTrue()))
-            // boolean
-            .describe(`boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE}`, () => expect(isType(TESTING_TRUE, 'boolean')).toBeTrue())
-                .it(`${TESTING_FALSE}`, () => expect(isType(TESTING_FALSE, 'boolean')).toBeTrue());
-            })
-            // null
-            .it(`${TESTING_NULL}`, () => expect(isType(TESTING_NULL, 'null')).toBeTrue())
-            // number
-            .describe(`number`, () => {
-              testing
-                .it(`${TESTING_NUMBER}`, () => expect(isType(TESTING_NUMBER, 'number')).toBeTrue())
-                .it(`Number(${TESTING_NUMBER})`, () => expect(isType(TESTING_NUMBER_CONSTRUCTOR, 'number')).toBeTrue());
-            })
-            // string
-            .describe(`string`, () => {
-              testing
-                .it(`${TESTING_STRING}`, () => expect(isType(TESTING_STRING, 'string')).toBeTrue())
-                .it(`String(${TESTING_STRING})`, () => expect(isType(TESTING_STRING_CONSTRUCTOR, 'string')).toBeTrue());
-            })
-            // symbol
-            .describe(`symbol`, () => {
-              testing
-                .it(`Symbol(${TESTING_NUMBER})`, () => expect(isType(TESTING_SYMBOL_NUMBER, 'symbol')).toBeTrue())
-                .it(`Symbol(${TESTING_STRING})`, () => expect(isType(TESTING_SYMBOL_STRING, 'symbol')).toBeTrue());
-            })
-            // undefined
-            .it(`${TESTING_UNDEFINED}`, () => expect(isType(TESTING_UNDEFINED, 'undefined')).toBeTrue())
-            // ... object.
-            .describe(`object`, () => {
-              testing
-                // BigInt
-                .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isType(TESTING_BIGINT, 'bigint')).toBeTrue()))
-                // Boolean
-                .describe(`Boolean`, () => {
-                  testing
-                    .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isType(TESTING_TRUE_INSTANCE, 'boolean')).toBeFalse())
-                    .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isType(TESTING_FALSE_INSTANCE, 'boolean')).toBeFalse());
-                })
-                // Number
-                .describe(`Number`, () =>
-                  testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isType(TESTING_NUMBER_INSTANCE, 'number')).toBeFalse()))
-                // String
-                .describe(`String`, () =>
-                  testing.it(`new String(${TESTING_STRING})`, () => expect(isType(TESTING_STRING_INSTANCE, 'string')).toBeFalse()));
-            });
-        });
-    });
-});
diff --git a/src/is/test/is-undefined.spec.ts b/src/is/test/is-undefined.spec.ts
deleted file mode 100644
index ddb50fd0..00000000
--- a/src/is/test/is-undefined.spec.ts
+++ /dev/null
@@ -1,127 +0,0 @@
-// Function.
-import { isUndefined } from '../lib/is-undefined.func';
-// Testing.
-import {
-  // Main.
-  Testing,
-
-  // Constant.
-  TESTING_BIGINT,
-  TESTING_CLASS,
-  TESTING_FALSE,
-  TESTING_FALSE_INSTANCE,
-  TESTING_FUNCTION,
-  TESTING_NULL,
-  TESTING_NUMBER,
-  TESTING_NUMBER_CONSTRUCTOR,
-  TESTING_NUMBER_INSTANCE,
-  TESTING_OBJECT,
-  TESTING_STRING,
-  TESTING_STRING_CONSTRUCTOR,
-  TESTING_STRING_INSTANCE,
-  TESTING_SYMBOL_NUMBER,
-  TESTING_SYMBOL_STRING,
-  TESTING_TRUE,
-  TESTING_TRUE_INSTANCE,
-  TESTING_UNDEFINED,
-
-  // Class.
-  TestingClass,
-} from '@angular-package/testing';
-// Execute tests.
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.is.undefined.describe,
-  tests.is.undefined.it
-);
-/**
- * Tests.
- */
-testing.describe(isUndefined.name, () => {
-  testing
-    // Defined.
-    .it('is DEFINED', () => expect(isUndefined).toBeDefined())
-
-    // Checks ...
-    .describe(`checks`, () => {
-      testing.it('callback', () => {
-        isUndefined(TESTING_STRING, (result: boolean) => {
-          expect(result).toBeFalse();
-          return result;
-        });
-      })
-
-      // ... arrays.
-      .describe(`array`, () => {})
-
-      // ... function.
-      .describe(`function`, () => {
-        testing
-          .it(`TESTING_FUNCTION`, () => expect(isUndefined(TESTING_FUNCTION)).toBeFalse())
-          .it(`TestingClass`, () => expect(isUndefined(TestingClass)).toBeFalse());
-      })
-
-      // ... objects.
-      .describe('object', () => {
-        testing
-          .it(`TESTING_CLASS`, () => expect(isUndefined(TESTING_CLASS)).toBeFalse())
-          .it(`TESTING_OBJECT`, () => expect(isUndefined(TESTING_OBJECT)).toBeFalse());
-      })
-
-      // ... primitives.
-      .describe(`primitive`, () => {
-        testing
-          // bigint
-          .describe(`bigint`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isUndefined(TESTING_BIGINT)).toBeFalse()))
-          // boolean
-          .describe(`boolean`, () => {
-            testing
-              .it(`${TESTING_TRUE}`, () => expect(isUndefined(TESTING_TRUE)).toBeFalse())
-              .it(`${TESTING_FALSE}`, () => expect(isUndefined(TESTING_FALSE)).toBeFalse());
-          })
-          // null
-          .it(`${TESTING_NULL}`, () => expect(isUndefined(TESTING_NULL)).toBeFalse())
-          // number
-          .describe(`number`, () => {
-            testing
-              .it(`${TESTING_NUMBER}`, () => expect(isUndefined(TESTING_NUMBER)).toBeFalse())
-              .it(`Number(${TESTING_NUMBER})`, () => expect(isUndefined(TESTING_NUMBER_CONSTRUCTOR)).toBeFalse());
-          })
-          // string
-          .describe(`string`, () => {
-            testing
-              .it(`${TESTING_STRING}`, () => expect(isUndefined(TESTING_STRING)).toBeFalse())
-              .it(`String(${TESTING_STRING})`, () => expect(isUndefined(TESTING_STRING_CONSTRUCTOR)).toBeFalse());
-          })
-          // symbol
-          .describe(`symbol`, () => {
-            testing
-              .it(`Symbol(${TESTING_NUMBER})`, () => expect(isUndefined(TESTING_SYMBOL_NUMBER)).toBeFalse())
-              .it(`Symbol(${TESTING_STRING})`, () => expect(isUndefined(TESTING_SYMBOL_STRING)).toBeFalse());
-          })
-          // undefined
-          .it(`${TESTING_UNDEFINED}`, () => expect(isUndefined(TESTING_UNDEFINED)).toBeTrue())
-          // ... object.
-          .describe(`object`, () => {
-            testing
-            // BigInt
-            .describe(`BigInt`, () => testing.it(`${TESTING_BIGINT}`, () => expect(isUndefined(TESTING_BIGINT)).toBeFalse()))
-            // Boolean
-            .describe(`Boolean`, () => {
-              testing
-                .it(`${TESTING_TRUE_INSTANCE}`, () => expect(isUndefined(TESTING_TRUE_INSTANCE)).toBeFalse())
-                .it(`${TESTING_FALSE_INSTANCE}`, () => expect(isUndefined(TESTING_FALSE_INSTANCE)).toBeFalse());
-            })
-            // Number
-            .describe(`Number`, () =>
-              testing.it(`new Number(${TESTING_NUMBER})`, () => expect(isUndefined(TESTING_NUMBER_INSTANCE)).toBeFalse()))
-            // String
-            .describe(`String`, () =>
-              testing.it(`new String(${TESTING_STRING})`, () => expect(isUndefined(TESTING_STRING_INSTANCE)).toBeFalse()));
-          });
-      });
-    });
-});
diff --git a/src/is/test/is.spec.ts b/src/is/test/is.spec.ts
deleted file mode 100644
index f0294a94..00000000
--- a/src/is/test/is.spec.ts
+++ /dev/null
@@ -1,51 +0,0 @@
-// Object.
-import { is } from '../lib/is.object';
-// Testing.
-import { Testing } from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-/**
- * Initialize testing.
- */
-const testing = new Testing(
-  tests.object.is.describe,
-  tests.object.is.it
-);
-/**
- * Tests.
- */
-testing.describe('`is{}`', () => {
-  testing
-    .describe('DEFINED', () => {
-      testing
-      .it('is', () => expect(is).toBeDefined())
-      .it('is.array()', () => expect(is.array).toBeDefined())
-      .it('is.boolean()', () => expect(is.boolean).toBeDefined())
-      .it('is.booleanObject()', () => expect(is.booleanObject).toBeDefined())
-      .it('is.booleanType()', () => expect(is.booleanType).toBeDefined())
-      .it('is.date()', () => expect(is.date).toBeDefined())
-      .it('is.defined()', () => expect(is.defined).toBeDefined())
-      .it('is.false()', () => expect(is.false).toBeDefined())
-      .it('is.function()', () => expect(is.function).toBeDefined())
-      .it('is.instance()', () => expect(is.instance).toBeDefined())
-      .it('is.key()', () => expect(is.key).toBeDefined())
-      .it('is.null()', () => expect(is.null).toBeDefined())
-      .it('is.number()', () => expect(is.number).toBeDefined())
-      .it('is.numberBetween()', () => expect(is.numberBetween).toBeDefined())
-      .it('is.numberObject()', () => expect(is.numberObject).toBeDefined())
-      .it('is.numberType()', () => expect(is.numberType).toBeDefined())
-      .it('is.object()', () => expect(is.object).toBeDefined())
-      .it('is.objectKey()', () => expect(is.objectKey).toBeDefined())
-      .it('is.objectKeyIn()', () => expect(is.objectKeyIn).toBeDefined())
-      .it('is.objectKeys()', () => expect(is.objectKeys).toBeDefined())
-      .it('is.primitive()', () => expect(is.primitive).toBeDefined())
-      .it('is.regexp()', () => expect(is.regexp).toBeDefined())
-      .it('is.string()', () => expect(is.string).toBeDefined())
-      .it('is.stringLength()', () => expect(is.stringLength).toBeDefined())
-      .it('is.stringObject()', () => expect(is.stringObject).toBeDefined())
-      .it('is.stringType()', () => expect(is.stringType).toBeDefined())
-      .it('is.symbol()', () => expect(is.symbol).toBeDefined())
-      .it('is.true()', () => expect(is.true).toBeDefined())
-      .it('is.type()', () => expect(is.type).toBeDefined())
-      .it('is.undefined()', () => expect(is.undefined).toBeDefined());
-   });
-});
diff --git a/src/lib/index.ts b/src/lib/index.ts
deleted file mode 100644
index a81a4d9a..00000000
--- a/src/lib/index.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-// Object.
-export { type } from './type.object';
-// Function.
-export { resultCallback } from './result-callback.func';
-export { typeOf } from './type-of.func';
diff --git a/src/lib/result-callback.func.ts b/src/lib/result-callback.func.ts
deleted file mode 100644
index 278a6081..00000000
--- a/src/lib/result-callback.func.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-/**
- * Default function to handle `callback` of functions.
- * @param result A value of `boolean` type of the result of the check.
- * @returns The return value is a `boolean` of the result of the check.
- */
-export const resultCallback = (result: boolean): boolean => result;
diff --git a/src/lib/type-of.func.ts b/src/lib/type-of.func.ts
deleted file mode 100644
index 4c0d7818..00000000
--- a/src/lib/type-of.func.ts
+++ /dev/null
@@ -1,8 +0,0 @@
-/**
- * Gets the specific object class type of any value.
- * @param value Any value to check its object class type.
- * @author https://javascript.plainenglish.io/the-best-way-to-type-check-in-vanilla-js-55197b4f45ec
- * @returns The return value is a `string` of the object class name.
- */
-export const typeOf = (value: any): string =>
-  Object.prototype.toString.call(value).slice(8, -1).toLowerCase();
diff --git a/src/lib/type.object.ts b/src/lib/type.object.ts
deleted file mode 100644
index 1e177e20..00000000
--- a/src/lib/type.object.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-// Object.
-import { are } from '../are/lib/are.object';
-import { guard } from '../guard/lib/guard.object';
-import { is } from '../is/lib/is.object';
-/**
- * The `object` consists of `are`, `is` and `guard` objects.
- */
-export const type = Object.freeze({
-  /**
-   * The object consists of `are` functions.
-   */
-  are,
-
-  /**
-   * The object consists of `is` functions.
-   */
-  is,
-
-  /**
-   * The `object` consists of `guard` functions.
-   */
-  guard
-});
diff --git a/src/public-api.ts b/src/public-api.ts
deleted file mode 100644
index 59d037b8..00000000
--- a/src/public-api.ts
+++ /dev/null
@@ -1,175 +0,0 @@
-/*
- * Public API Surface of type.
- */
-/*
- * Main.
- */
-export {
-  // Object.
-  type, // From the 5.0.0 version
-
-  // Function.
-  typeOf
-} from './lib';
-
-/*
- * Recognize.
- */
-export {
-  recognizeValue // From the 5.0.0 version
-} from './recognize';
-
-/*
- * Are.
- */
-export {
-  // Object.
-  are,
-
-  // Function.
-  areBigInt,
-  areBoolean,
-  areDate,
-  areDefined,
-  areFalse,
-  areNull,
-  areNumber,
-  areRegExp,
-  areString,
-  areSymbol,
-  areTrue,
-  areUndefined,
-} from './are';
-
-/*
- * Is.
- */
-export {
-  // Object.
-  is,
-
-  // Function.
-  isArray,
-  isBigInt,
-  isBoolean,
-  isBooleanObject,
-  isBooleanType,
-  isClass,
-  isDate, // From the 4.2.0 version.
-  isDefined,
-  isFalse, // From the 4.2.0 version.
-  isFunction,
-  isInstance,
-  isKey,
-  isNull,
-  isNumber,
-  isNumberBetween, // From the 4.2.0 version.
-  isNumberObject,
-  isNumberType,
-  isObject,
-  isObjectKey,
-  isObjectKeyIn,
-  isObjectKeys,
-  isObjectKeysIn, // From the 5.0.0 version
-  isObjectSomeKeys, // From the 5.0.0 version
-  isParam,
-  isPrimitive,
-  isRegExp, // From the 4.2.0 version.
-  isString,
-  isStringIncludes, // From the 5.0.0 version
-  isStringIncludesSome, // From the 5.0.0 version
-  isStringLength, // From the 4.2.0 version.
-  isStringLengthBetween, // From the 5.0.0 version
-  isStringObject,
-  isStringType,
-  isSymbol,
-  isTrue, // From the 4.2.0 version.
-  isType,
-  isUndefined,
-} from './is';
-
-/*
- * isNot.
- */
-export {
-  // Object.
-  isNot,
-
-  // Function.
-  isNotBoolean,
-  isNotDefined,
-  isNotFunction,
-  isNotNull,
-  isNotNumber,
-  isNotString,
-  isNotUndefined,
-} from './is/not';
-
-/*
- * Guard.
- */
-export {
-  // Object.
-  guard,
-
-  // Function.
-  guardArray,
-  guardBigInt,
-  guardBoolean,
-  guardClass,
-  guardDate, // From the 5.0.0 version
-  guardDefined,
-  guardFalse, // From the 5.0.0 version
-  guardFunction,
-  guardInstance,
-  guardKey,
-  guardNull,
-  guardNumber,
-  guardNumberBetween, // From the 5.0.0 version
-  guardObject,
-  guardObjectKey,
-  guardObjectKeyIn, // From the 5.0.0 version
-  guardObjectKeys,
-  guardObjectKeysIn, // From the 5.0.0 version
-  guardObjectSomeKeys, // From the 5.0.0 version
-  guardPrimitive,
-  guardRegExp, // From the 5.0.0 version
-  guardString,
-  guardStringIncludes, // From the 5.0.0 version
-  guardStringIncludesSome, // From the 5.0.0 version
-  guardStringLength, // From the 5.0.0 version
-  guardStringLengthBetween, // From the 5.0.0 version
-  guardSymbol,
-  guardTrue, // From the 5.0.0 version
-  guardType,
-  guardUndefined,
-} from './guard';
-
-/*
- * Interface.
- */
-export {
-  MinMax  // From the 5.0.0 version
-} from './interface';
-
-/*
- * Type.
- */
-export { AnyBoolean } from './type/any-boolean.type';
-export { AnyNumber } from './type/any-number.type';
-export { AnyString } from './type/any-string.type';
-export { CallbackPayload } from './type/callback-payload.type';
-export { Constructor } from './type/constructor.type';
-export { Defined } from './type/defined.type';
-export { ForEachCallback } from './type/foreach-callback.type';
-export { GenericObject } from './type/generic-object.type';
-export { Never } from './type/never.type';
-export { NotUndefined } from './type/not-undefined.type';
-export { NumberBetween } from './type/number-between.type';
-export { Primitive } from './type/primitive.type';
-export { Primitives } from './type/primitives.type';
-export { ResultCallback } from './type/result-callback.type';
-export { StringOfLength } from './type/string-of-length.type';
-export { Type } from './type/type.type';
-export { Types } from './type/types.type';
-export { Undefined } from './type/undefined.type';
diff --git a/src/recognize/index.ts b/src/recognize/index.ts
deleted file mode 100644
index 0befa95e..00000000
--- a/src/recognize/index.ts
+++ /dev/null
@@ -1 +0,0 @@
-export { recognizeValue } from './src/recognize-value.func';
diff --git a/src/recognize/src/recognize-instances.const.ts b/src/recognize/src/recognize-instances.const.ts
deleted file mode 100644
index a53ebd42..00000000
--- a/src/recognize/src/recognize-instances.const.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-/**
- * An `Array` of default objects to check by using the `instanceof` operator.
- */
-export const RECOGNIZE_INSTANCES = [
-  Array,
-  ArrayBuffer,
-  Boolean,
-  DataView,
-  Date,
-  Error,
-  EvalError,
-  Float32Array,
-  Float64Array,
-  Function,
-  Int16Array,
-  Int32Array,
-  Int8Array,
-  Map,
-  Number,
-  Object,
-  Promise,
-  RangeError,
-  ReferenceError,
-  RegExp,
-  Set,
-  Storage,
-  String,
-  SyntaxError,
-  TypeError,
-  URIError,
-  Uint16Array,
-  Uint32Array,
-  Uint8Array,
-  Uint8ClampedArray,
-  WeakMap,
-  WeakSet
-];
diff --git a/src/recognize/src/recognize-value.func.ts b/src/recognize/src/recognize-value.func.ts
deleted file mode 100644
index 9fdef1d4..00000000
--- a/src/recognize/src/recognize-value.func.ts
+++ /dev/null
@@ -1,51 +0,0 @@
-// Object.
-import { is } from '../../is/lib/is.object';
-// Function.
-import { typeOf } from '../../lib/type-of.func';
-// Type.
-import { OfRecognized } from '../type/of-recognized.type';
-// Const.
-import { RECOGNIZE_INSTANCES } from './recognize-instances.const';
-/**
- * Gets recognized types and instances of given `value`.
- * @param value The value of any type to recognize.
- * @param onlyTrue Determines whether or not show only recognized as `true`.
- * @param instances An optional array of objects to check by using `instanceof` operator.
- * @returns The return value is an object of types and instances recognized as `true` or all even those recognized as `false`.
- */
-export const recognizeValue = (
-  value: any,
-  onlyTrue: boolean = true,
-  instances: any[] = []
-): OfRecognized => {
-  // Recognize types.
-  const ofRecognized: OfRecognized = {
-    'Array.isArray': Array.isArray(value),
-    isClass: is.class(value),
-    isFunction: is.function(value),
-    'Number.isInteger': Number.isInteger(value),
-    'Number.isFinite': Number.isFinite(value),
-    'Number.isNaN': Number.isNaN(value),
-    'Number.isSafeInteger': Number.isSafeInteger(value),
-    typeOf: typeOf(value),
-    typeof: typeof value,
-  };
-
-  try { Object.assign(ofRecognized, { isFinite: isFinite(value) }); } catch (e) {}
-  try { Object.assign(ofRecognized, { isNaN: isNaN(value) }); } catch (e) {}
-
-  // Recognize instances.
-  RECOGNIZE_INSTANCES.concat(instances as any).forEach((instance) => (
-    Object.assign(ofRecognized, { [instance.name]: value instanceof instance })
-  ));
-
-  // If only true remove false.
-  if (is.true(onlyTrue)) {
-    Object.keys(ofRecognized).filter((type: string) =>
-      is.false(ofRecognized[type as keyof OfRecognized])
-        ? delete ofRecognized[type as keyof OfRecognized]
-        : true
-    );
-  }
-  return ofRecognized;
-};
diff --git a/src/recognize/test/recognize-value.spec.ts b/src/recognize/test/recognize-value.spec.ts
deleted file mode 100644
index 451467ba..00000000
--- a/src/recognize/test/recognize-value.spec.ts
+++ /dev/null
@@ -1,360 +0,0 @@
-// Testing.
-import { Testing } from '@angular-package/testing';
-import { tests } from '../../execute-tests';
-// Function.
-import { recognizeValue } from '../src/recognize-value.func';
-/*
-  Initialize testing.
- */
-const testing = new Testing(
-  tests.recognize.recognizeValue.describe,
-  tests.recognize.recognizeValue.it
-);
-
-class CustomClass {}
-const customClass = new CustomClass();
-
-const firstName = 'Artemis';
-
-
-/*
-  Tests.
-*/
-testing.describe(recognizeValue.name, () =>
-  testing
-    .toEqual(`NaN`, recognizeValue(NaN), {
-      'Number.isNaN': true,
-      isNaN: true,
-      typeOf: 'number',
-      typeof: 'number',
-    })
-
-    .toEqual(`Number.NaN`, recognizeValue(Number.NaN), {
-      'Number.isNaN': true,
-      isNaN: true,
-      typeOf: 'number',
-      typeof: 'number',
-    })
-
-    .toEqual(`0 / 0`, recognizeValue(0 / 0), {
-      'Number.isNaN': true,
-      isNaN: true,
-      typeOf: 'number',
-      typeof: 'number',
-    })
-
-    .toEqual(`true`, recognizeValue(true), {
-      isFinite: true,
-      typeOf: 'boolean',
-      typeof: 'boolean',
-    })
-
-    .toEqual(`'NaN'`, recognizeValue('NaN'), {
-      isNaN: true,
-      typeOf: 'string',
-      typeof: 'string',
-    })
-
-    .toEqual(`string = 2.0`, recognizeValue('2.0'), {
-      isFinite: true,
-      typeOf: 'string',
-      typeof: 'string',
-    })
-
-    .toEqual(`new String(firstName)`, recognizeValue(new String(firstName)), {
-      typeOf: 'string',
-      typeof: 'object',
-      isNaN: true,
-      Object: true,
-      String: true,
-    })
-
-    .toEqual(`CustomClass`, recognizeValue(customClass, true, [CustomClass]), {
-      CustomClass: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'object',
-      typeof: 'object',
-    })
-
-    .toEqual(`CustomClass`, recognizeValue(CustomClass, true, [CustomClass]), {
-      Function: true,
-      Object: true,
-      isClass: true,
-      isNaN: true,
-      typeOf: 'function',
-      typeof: 'function',
-    })
-
-    .toEqual(`new Array()`, recognizeValue(new Array()), {
-      Array: true,
-      Object: true,
-      'Array.isArray': true,
-      isFinite: true,
-      typeOf: 'array',
-      typeof: 'object',
-    })
-
-    .toEqual(`Array`, recognizeValue(Array), {
-      Function: true,
-      Object: true,
-      isFunction: true,
-      isNaN: true,
-      typeOf: 'function',
-      typeof: 'function',
-    })
-
-    .toEqual(`new ArrayBuffer(50)`, recognizeValue(new ArrayBuffer(50)), {
-      ArrayBuffer: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'arraybuffer',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Boolean()`, recognizeValue(new Boolean()), {
-      Boolean: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'boolean',
-      typeof: 'object',
-    })
-
-    .toEqual(
-      `new DataView(new ArrayBuffer(16))`,
-      recognizeValue(new DataView(new ArrayBuffer(16))), {
-        DataView: true,
-        Object: true,
-        isNaN: true,
-        typeOf: 'dataview',
-        typeof: 'object'
-      }
-    )
-
-    .toEqual(`new Date()`, recognizeValue(new Date()), {
-      Date: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'date',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Error()`, recognizeValue(new Error()), {
-      Error: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new EvalError()`, recognizeValue(new EvalError()), {
-      Error: true,
-      EvalError: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Int16Array()`, recognizeValue(new Int16Array()), {
-      Int16Array: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'int16array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Int32Array()`, recognizeValue(new Int32Array()), {
-      Int32Array: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'int32array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Int8Array()`, recognizeValue(new Int8Array()), {
-      Int8Array: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'int8array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Map()`, recognizeValue(new Map()), {
-      Map: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'map',
-      typeof: 'object',
-    })
-
-    // .toEqual(`new Promise((resolve, reject) => {
-    //   setTimeout(() => {
-    //     resolve('foo');
-    //   }, 300);
-    // })`, recognizeValue(new Promise((resolve, reject) => {
-    //   setTimeout(() => {
-    //     resolve('foo');
-    //   }, 300);
-    // })), {Promise: true, Object: true, typeOf: 'promise', typeof: 'object'})
-
-    .toEqual(`new RangeError()`, recognizeValue(new RangeError()), {
-      Error: true,
-      Object: true,
-      RangeError: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new ReferenceError()`, recognizeValue(new ReferenceError()), {
-      Error: true,
-      ReferenceError: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new RegExp(/[^]/g)`, recognizeValue(new RegExp(/[^]/g)), {
-      typeOf: 'regexp',
-      typeof: 'object',
-      isNaN: true,
-      Object: true,
-      RegExp: true,
-    })
-
-    .toEqual(`new Set()`, recognizeValue(new Set()), {
-      Object: true,
-      Set: true,
-      isNaN: true,
-      typeOf: 'set',
-      typeof: 'object',
-    })
-
-    .toEqual(`new SyntaxError()`, recognizeValue(new SyntaxError()), {
-      Error: true,
-      SyntaxError: true,
-      Object: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Float32Array()`, recognizeValue(new Float32Array()), {
-      Float32Array: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'float32array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Float64Array()`, recognizeValue(new Float64Array()), {
-      Float64Array: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'float64array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Function()`, recognizeValue(new Function()), {
-      Function: true,
-      Object: true,
-      isFunction: true,
-      isNaN: true,
-      typeOf: 'function',
-      typeof: 'function',
-    })
-
-    .toEqual(`new Number(5)`, recognizeValue(new Number(5)), {
-      Number: true,
-      Object: true,
-      isFinite: true,
-      typeOf: 'number',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Object()`, recognizeValue(new Object()), {
-      Object: true,
-      isNaN: true,
-      typeOf: 'object',
-      typeof: 'object',
-    })
-
-    .toEqual(`new String()`, recognizeValue(new String()), {
-      Object: true,
-      String: true,
-      isFinite: true,
-      typeOf: 'string',
-      typeof: 'object',
-    })
-
-    .toEqual(`new TypeError()`, recognizeValue(new TypeError()), {
-      Error: true,
-      Object: true,
-      TypeError: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Uint16Array()`, recognizeValue(new Uint16Array()), {
-      Object: true,
-      Uint16Array: true,
-      isFinite: true,
-      typeOf: 'uint16array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Uint32Array()`, recognizeValue(new Uint32Array()), {
-      Object: true,
-      Uint32Array: true,
-      isFinite: true,
-      typeOf: 'uint32array',
-      typeof: 'object',
-    })
-
-    .toEqual(`new Uint8Array()`, recognizeValue(new Uint8Array()), {
-      Object: true,
-      Uint8Array: true,
-      isFinite: true,
-      typeOf: 'uint8array',
-      typeof: 'object',
-    })
-
-    .toEqual(
-      `new Uint8ClampedArray()`,
-      recognizeValue(new Uint8ClampedArray()), {
-        Object: true,
-        Uint8ClampedArray: true,
-        isFinite: true,
-        typeOf: 'uint8clampedarray',
-        typeof: 'object',
-      }
-    )
-
-    .toEqual(`new URIError()`, recognizeValue(new URIError()), {
-      Error: true,
-      Object: true,
-      URIError: true,
-      isNaN: true,
-      typeOf: 'error',
-      typeof: 'object',
-    })
-
-    .toEqual(`new WeakMap()`, recognizeValue(new WeakMap()), {
-      Object: true,
-      WeakMap: true,
-      isNaN: true,
-      typeOf: 'weakmap',
-      typeof: 'object',
-    })
-
-    .toEqual(`new WeakSet()`, recognizeValue(new WeakSet()), {
-      Object: true,
-      WeakSet: true,
-      isNaN: true,
-      typeOf: 'weakset',
-      typeof: 'object',
-    })
-);
diff --git a/src/recognize/type/of-recognized.type.ts b/src/recognize/type/of-recognized.type.ts
deleted file mode 100644
index 1550ed88..00000000
--- a/src/recognize/type/of-recognized.type.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-export interface OfRecognized {
-  // Proxy?: boolean;
-  Array?: boolean;
-  ArrayBuffer?: boolean;
-  Boolean?: boolean;
-  DataView?: boolean;
-  Date?: boolean;
-  Error?: boolean;
-  EvalError?: boolean;
-  Float32Array?: boolean;
-  Float64Array?: boolean;
-  Function?: boolean;
-  Int16Array?: boolean;
-  Int32Array?: boolean;
-  Int8Array?: boolean;
-  Map?: boolean;
-  Number?: boolean;
-  Object?: boolean;
-  Promise?: boolean;
-  RangeError?: boolean;
-  ReferenceError?: boolean;
-  RegExp?: boolean;
-  Set?: boolean;
-  SharedArrayBuffer?: boolean;
-  Storage?: boolean;
-  String?: boolean;
-  Symbol?: boolean;
-  SyntaxError?: boolean;
-  TypeError?: boolean;
-  URIError?: boolean;
-  Uint16Array?: boolean;
-  Uint32Array?: boolean;
-  Uint8Array?: boolean;
-  Uint8ClampedArray?: boolean;
-  WeakMap?: boolean;
-  WeakSet?: boolean;
-  // Array.isArray()
-  'Array.isArray'?: boolean;
-  // isClass()
-  isClass?: boolean;
-  // isFunction()
-  isFunction?: boolean;
-  // isFinite()
-  isFinite?: boolean;
-  // isInteger()
-  'Number.isInteger'?: boolean;
-  // isNaN()
-  isNaN?: boolean;
-  // Number.isNaN()
-  'Number.isNaN'?: boolean;
-  // Number.isFinite()
-  'Number.isFinite'?: boolean;
-  // typeOf()
-  typeOf?: string;
-  // operator typeof
-  typeof?: string;
-
-  [index: string]: boolean | string | undefined;
-}
diff --git a/src/test.ts b/src/test.ts
deleted file mode 100644
index a7d1b428..00000000
--- a/src/test.ts
+++ /dev/null
@@ -1,28 +0,0 @@
-// This file is required by karma.conf.js and loads recursively all the .spec and framework files
-
-import 'zone.js/dist/zone';
-import 'zone.js/dist/zone-testing';
-import { getTestBed } from '@angular/core/testing';
-import {
-  BrowserDynamicTestingModule,
-  platformBrowserDynamicTesting
-} from '@angular/platform-browser-dynamic/testing';
-
-declare const require: {
-  context(path: string, deep?: boolean, filter?: RegExp): {
-    keys(): string[];
-    <T>(id: string): T;
-  };
-};
-
-// First, initialize the Angular testing environment.
-getTestBed().initTestEnvironment(
-  BrowserDynamicTestingModule,
-  platformBrowserDynamicTesting(), {
-    teardown: { destroyAfterEach: false }
-}
-);
-// Then we find all the tests.
-const context = require.context('./', true, /\.spec\.ts$/);
-// And load the modules.
-context.keys().map(context);
diff --git a/src/type/any-boolean.type.ts b/src/type/any-boolean.type.ts
deleted file mode 100644
index 835c7619..00000000
--- a/src/type/any-boolean.type.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/**
- * A `boolean` type or an instance of a `Boolean`.
- */
-export type AnyBoolean = Exclude<boolean | Boolean, true | false>;
diff --git a/src/type/any-number.type.ts b/src/type/any-number.type.ts
deleted file mode 100644
index e8512b4c..00000000
--- a/src/type/any-number.type.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/**
- * A `number` type or an instance of a `Number`.
- */
-export type AnyNumber = number | Number;
diff --git a/src/type/any-string.type.ts b/src/type/any-string.type.ts
deleted file mode 100644
index f424eeb8..00000000
--- a/src/type/any-string.type.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/**
- * A `string` type or an instance of a `String`.
- */
-export type AnyString = string | String;
diff --git a/src/type/callback-payload.type.ts b/src/type/callback-payload.type.ts
deleted file mode 100644
index e586573f..00000000
--- a/src/type/callback-payload.type.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-import { GenericObject } from './generic-object.type';
-/**
- * Experimental shape for a generic type variable `Payload`.
- */
-export type CallbackPayload<Payload = object> = GenericObject & {
-
-  /**
-   * An optional action of a `string` type that describes the cause of performed callback.
-   */
-  action?: string;
-
-  /**
-   * An optional name of the function or method of a `string` type that performed callback.
-   */
-  name?: string;
-
-  /**
-   * An optional name of the parameter of a `string` type to which performed callback relates.
-   */
-  param?: string;
-
-} & Payload;
diff --git a/src/type/constructor.type.ts b/src/type/constructor.type.ts
deleted file mode 100644
index e5798954..00000000
--- a/src/type/constructor.type.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/**
- * An instance of a type from the provided generic type variable `Type`.
- */
-export type Constructor<Type> = new (...args: any[]) => Type;
diff --git a/src/type/defined.type.ts b/src/type/defined.type.ts
deleted file mode 100644
index 7bb13d22..00000000
--- a/src/type/defined.type.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-/**
- * A generic type `Defined` indicates the generic type variable `Type` is never `undefined`.
- * It takes generic type variable `Type` constrained by `undefined` by using `Never` which constraint causes its change to `never`.
- */
-export type Defined<Type> = Type extends undefined ? never : Type;
diff --git a/src/type/foreach-callback.type.ts b/src/type/foreach-callback.type.ts
deleted file mode 100644
index 21d4ec84..00000000
--- a/src/type/foreach-callback.type.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-/**
- * Represents a callback function of `forEach()` method which is executed once for each element.
- * @param result The result of the check of a `boolean` type.
- * @param value The value that has been checked of a generic type variable `Value`.
- * @param index An optional `number` of checked `array` element.
- * @param array An optional `array` of `any` type that each element is checked.
- * @param payload An optional `object` of a generic type variable `Payload` to provide more data.
- * @returns The return value is void.
- */
-export type ForEachCallback<Value = any, Payload = object> = (
-  result: boolean,
-  value: Value,
-  index: number,
-  array: any[],
-  payload?: Payload
-) => void;
diff --git a/src/type/generic-object.type.ts b/src/type/generic-object.type.ts
deleted file mode 100644
index 771f2b07..00000000
--- a/src/type/generic-object.type.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-/**
- * The type of generic object that takes generic type variable `Value`.
- */
-export type GenericObject<Value = any> = {
-  [index: string]: Value;
-};
diff --git a/src/type/never.type.ts b/src/type/never.type.ts
deleted file mode 100644
index af0e0343..00000000
--- a/src/type/never.type.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-/**
- * A generic type `Never` indicates the generic type variable `Type` is never of the generic type variable `Not`.
- * It takes generic type variable `Type` constrained by a generic type variable `Not` which constraint causes its change to `never`.
- */
-export type Never<Not, Type> = Type extends Not ? never : Type;
diff --git a/src/type/not-undefined.type.ts b/src/type/not-undefined.type.ts
deleted file mode 100644
index 68384e2a..00000000
--- a/src/type/not-undefined.type.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-/**
- * A generic type `NotUndefined` represents any type instead of `undefined`. It takes generic type variable `Type` constrained by
- * `undefined` which constraint causes its change to `never`.
- */
-export type NotUndefined<Type> = Type extends undefined ? never : Type;
diff --git a/src/type/number-between.type.ts b/src/type/number-between.type.ts
deleted file mode 100644
index 6e88a903..00000000
--- a/src/type/number-between.type.ts
+++ /dev/null
@@ -1,13 +0,0 @@
-// Type.
-import { AnyNumber } from './any-number.type';
-// Interface.
-import { MinMax } from '../interface/min-max.interface';
-/**
- * A `number` type or an instance of `Number` between a specified range takes generic type variable `Min` and `Max` constrained by `number`
- * type as range, and takes generic type variable `Type` constrained by generic type `AnyNumber` as the type.
- */
-export type NumberBetween<
-  Min extends number,
-  Max extends number,
-  Type extends AnyNumber = number
-> = Type & MinMax<Min, Max>;
diff --git a/src/type/primitive.type.ts b/src/type/primitive.type.ts
deleted file mode 100644
index c8404c2d..00000000
--- a/src/type/primitive.type.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-/**
- * All primitives types.
- */
-export type Primitive =
-  | boolean
-  | bigint
-  | null
-  | number
-  | string
-  | symbol
-  | undefined;
diff --git a/src/type/primitives.type.ts b/src/type/primitives.type.ts
deleted file mode 100644
index 44a0f5ef..00000000
--- a/src/type/primitives.type.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-/**
- * All primitives types as `string`.
- */
-export type Primitives =
-  | 'bigint'
-  | 'boolean'
-  | 'null'
-  | 'number'
-  | 'string'
-  | 'symbol'
-  | 'undefined';
diff --git a/src/type/result-callback.type.ts b/src/type/result-callback.type.ts
deleted file mode 100644
index bc94c232..00000000
--- a/src/type/result-callback.type.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-/**
- * Represents a callback function with parameters, the `value` that has been checked, the `result` of this check, and an optional
- * `payload`.
- * @var Value A generic type variable `Value` determines `value` parameter type, by default `any`.
- * @var Payload Generic type variable `Payload` indicates `payload` parameter type, by default `object`.
- * @param result The check result of a `boolean` type of the given `value`.
- * @param value The value of the generic type variable Value to check and which the given check `result` applies.
- * @param payload An optional `object` of a generic type variable `Payload` to provide more data.
- * @returns The return value is a `boolean` indicating the check result of the given `value`.
- */
- export type ResultCallback<Value = any, Payload = object> = (
-  result: boolean,
-  value: Value,
-  payload?: Payload
-) => boolean;
diff --git a/src/type/string-of-length.type.ts b/src/type/string-of-length.type.ts
deleted file mode 100644
index da5a8989..00000000
--- a/src/type/string-of-length.type.ts
+++ /dev/null
@@ -1,13 +0,0 @@
-// Interface.
-import { MinMax } from '../interface/min-max.interface';
-// Type.
-import { AnyString } from './any-string.type';
-/**
- * A `string` type or an instance of `String` of length between a specified range takes generic type variable `Min` and `Max` constrained by
- * `number` type as length, and takes generic type variable `Type` constrained by generic type `AnyString` as the type.
- */
-export type StringOfLength<
-  Min extends number,
-  Max extends number,
-  Type extends AnyString = string
-> = Type & MinMax<Min, Max>;
diff --git a/src/type/type.type.ts b/src/type/type.type.ts
deleted file mode 100644
index c0b1b53a..00000000
--- a/src/type/type.type.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-import { Primitive } from './primitive.type';
-/**
- * The main types consist of `Function`, `object`, and `Primitive`.
- */
-export type Type = Function | object | Primitive;
diff --git a/src/type/types.type.ts b/src/type/types.type.ts
deleted file mode 100644
index 1473fccc..00000000
--- a/src/type/types.type.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-import { Constructor } from './constructor.type';
-import { Primitives } from './primitives.type';
-/**
- * The main types as string values, besides the `Constructor` which is an instance of an Obj.
- */
-export type Types<Obj> = Constructor<Obj> | 'function' | 'object' | Primitives;
diff --git a/src/type/undefined.type.ts b/src/type/undefined.type.ts
deleted file mode 100644
index 8edf5f6b..00000000
--- a/src/type/undefined.type.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-/**
- * A generic type `Undefined` indicates generic type variable `Type` as undefined. It takes generic type variable `Type` causing other
- * types than `undefined` its change to never.
- */
-export type Undefined<Type> = Type extends undefined ? Type : never;
diff --git a/tsconfig.lib.json b/tsconfig.lib.json
deleted file mode 100644
index 7b5ac727..00000000
--- a/tsconfig.lib.json
+++ /dev/null
@@ -1,20 +0,0 @@
-/* To learn more about this file see: https://angular.io/config/tsconfig. */
-{
-  "extends": "../../tsconfig.json",
-  "compilerOptions": {
-    "outDir": "../../out-tsc/lib",
-    "target": "es2020",
-    "declaration": true,
-    "declarationMap": true,
-    "inlineSources": true,
-    "types": [],
-    "lib": [
-      "dom",
-      "es2020"
-    ]
-  },
-  "exclude": [
-    "src/test.ts",
-    "**/*.spec.ts"
-  ]
-}
diff --git a/tsconfig.lib.prod.json b/tsconfig.lib.prod.json
deleted file mode 100644
index 06de549e..00000000
--- a/tsconfig.lib.prod.json
+++ /dev/null
@@ -1,10 +0,0 @@
-/* To learn more about this file see: https://angular.io/config/tsconfig. */
-{
-  "extends": "./tsconfig.lib.json",
-  "compilerOptions": {
-    "declarationMap": false
-  },
-  "angularCompilerOptions": {
-    "compilationMode": "partial"
-  }
-}
diff --git a/tsconfig.spec.json b/tsconfig.spec.json
deleted file mode 100644
index 715dd0a5..00000000
--- a/tsconfig.spec.json
+++ /dev/null
@@ -1,17 +0,0 @@
-/* To learn more about this file see: https://angular.io/config/tsconfig. */
-{
-  "extends": "../../tsconfig.json",
-  "compilerOptions": {
-    "outDir": "../../out-tsc/spec",
-    "types": [
-      "jasmine"
-    ]
-  },
-  "files": [
-    "src/test.ts"
-  ],
-  "include": [
-    "**/*.spec.ts",
-    "**/*.d.ts"
-  ]
-}
diff --git a/tslint.json b/tslint.json
deleted file mode 100644
index 124133f8..00000000
--- a/tslint.json
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-  "extends": "../../tslint.json",
-  "rules": {
-    "directive-selector": [
-      true,
-      "attribute",
-      "lib",
-      "camelCase"
-    ],
-    "component-selector": [
-      true,
-      "element",
-      "lib",
-      "kebab-case"
-    ]
-  }
-}
