/**
  * Return active instance of this class, create one if it doesn't exist
  *
  * @return WP_Stream_Notifications
  */
 public static function get_instance()
 {
     if (empty(self::$instance)) {
         self::$instance = new self();
     }
     return self::$instance;
 }
 /**
  * Return active instance of WP_Stream, create one if it doesn't exist
  *
  * @return WP_Stream
  */
 public static function get_instance()
 {
     if (empty(self::$instance)) {
         $class = __CLASS__;
         self::$instance = new $class();
     }
     return self::$instance;
 }