WP_Widget_Pages::form

		$instance['title'] = sanitize_text_field( $new_instance['title'] );
		if ( in_array( $new_instance['sortby'], array( 'post_title', 'menu_order', 'ID' ), true ) ) {
			$instance['sortby'] = $new_instance['sortby'];
		} else {
			$instance['sortby'] = 'menu_order';
		}

		$instance['exclude'] = sanitize_text_field( $new_instance['exclude'] );

		return $instance;
	}

	/**
	 * Outputs the settings form for the Pages widget.
	 *
	 * @since 2.8.0
	 *
	 * @param array $instance Current settings.
	 */
	public function form( $instance ) {
		// Defaults.
		$instance = wp_parse_args(
			(array) $instance,
			array(
				'sortby'  => 'post_title',
				'title'   => '',
				'exclude' => '',
			)
		);
		?>
		<p>