*
	 * @return LLMS_Question_Manager
	 */
	public function questions() {
		return new LLMS_Question_Manager( $this );
	}

	/**
	 * Called before data is sorted and returned by $this->toArray().
	 * Extending classes should override this data if custom data should
	 * be added when object is converted to an array or json.
	 *
	 * @since 3.3.0
	 * @since 3.19.2 Unknown.
	 * @since 3.38.0 Only add theme metadata to the quiz array when the `llms_get_quiz_theme_settings` filter is being used.
	 *
	 * @param array $arr Array of data to be serialized.
	 * @return array
	 */
	protected function toArrayAfter( $arr ) {

		$arr['questions'] = array();