* @since 5.0.0 Load core libraries from new location, add WP Background Processing lib, add LLMS Helper.
	 * @since 5.1.3 Add keys to the $libs array and pass them through a filter.
	 * @since 5.5.0 Add LLMS-CLI to the list of included libraries.
	 *
	 * @return void
	 */
	public function includes_libraries() {

		$libs = array(
			'blocks' => array(
				'const' => 'LLMS_BLOCKS_LIB',
				'test'  => function_exists( 'has_blocks' ) && ! defined( 'LLMS_BLOCKS_VERSION' ),
				'file'  => LLMS_PLUGIN_DIR . 'libraries/lifterlms-blocks/lifterlms-blocks.php',
			),
			'cli'    => array(
				'const' => 'LLMS_CLI_LIB',
				'test'  => ! function_exists( 'llms_cli' ),
				'file'  => LLMS_PLUGIN_DIR . 'libraries/lifterlms-cli/lifterlms-cli.php',
			),
			'rest'   => array(
				'const' => 'LLMS_REST_API_LIB',
				'test'  => ! class_exists( 'LifterLMS_REST_API' ),
				'file'  => LLMS_PLUGIN_DIR . 'libraries/lifterlms-rest/lifterlms-rest.php',
			),
			'helper' => array(
				'const' => 'LLMS_HELPER_LIB',
				'test'  => ! class_exists( 'LifterLMS_Helper' ),
				'file'  => LLMS_PLUGIN_DIR . 'libraries/lifterlms-helper/lifterlms-helper.php',
			),
		);

		/**
		 * Filters the list of LifterLMS libraries to be loaded.
		 *
		 * @since 5.1.3
		 *
		 * @param array $libs {
		 *     Array of library data. Each array key serves as a unique ID for the library.
		 *
		 *     @type string $const Name of the constant used to identify if the library is loaded as a library.
		 *     @type bool   $test  A test which is evaluated to determine if the library should be loaded. Returning `false` causes the library not to load.
		 *     @type string $file  Path to the main library file's location in the LifterLMS core plugin.
		 * }
		 */
		$libs = apply_filters( 'llms_included_libs', $libs );
		foreach ( $libs as $lib ) {

			if ( $lib['test'] ) {
				define( $lib['const'], true );
				require_once $lib['file'];
			}
		}