/**
* Access this class's working instance.
* If the instance hasn't been set, set it now.
*
* @wp-hook void
* @uses void
* @since 2.0.0
* @return object of this class
*/
public static function get_instance()
{
if (null == self::$instance) {
self::$instance = new self();
}
return self::$instance;
}