private $_saved;

	/**
	 * Constructor.
	 *
	 * Configure the metabox and automatically add required actions.
	 *
	 * @since 3.0.0
	 * @since 3.37.12 Use `$this->error_opt_key()` in favor of hardcoded option name.
	 *
	 * @return void
	 */
	public function __construct() {

		// Allow child classes to configure variables.
		$this->configure();

		// Set the error option key.
		$this->error_opt_key = sprintf( 'lifterlms_metabox_errors%s', $this->id );

		// Register the metabox.
		add_action( 'add_meta_boxes', array( $this, 'register' ) );