Sibling Pages

class Sibling_Pages extends WP_Widget {

	public function __construct() {

		parent::__construct(
			'',
			__( 'Sibling Pages', 'sibling_pages' ),
			array(
				'description' => __( 'Display the current page's siblings.', 'sibling_pages' ),
				'classname'   => 'sibling-pages',
			)
		);

	}

	public function widget( $args, $instance ) {

<ul>
<li><a href="">Page</a></li>
</ul>

	}

	public function form( $instance ) {

	}

	public function update( $new_instance, $old_instance ) {

	}

}

function siblingpages_register_widgets() {
	register_widget( 'Sibling_Pages' );
}
add_action( 'widgets_init', 'siblingpages_register_widgets' );