protected function sortListeners( $eventName )
    {
        $this->_sorted[ $eventName ] = [ ];

        if ( isset( $this->listeners[ $eventName ] ) )
        {
            krsort( $this->listeners[ $eventName ] );
            $this->_sorted[ $eventName ] = call_user_func_array( 'array_merge', $this->listeners[ $eventName ] );
        }
    }