public static function onTransmission($event, $fn, $priority = 0)
    {
        if (!static::bound($event)) {
            static::$events['__bow.transmission.event'][$event] = [];
        }

        if (!is_string($fn)) {
            throw new EventException('The transmission event must be a string function name');
        }

        static::$events['__bow.transmission.event'][$event][] = new Listener($fn, $priority);

        Session::getInstance()->add("__bow.event.listener", static::$events['__bow.transmission.event']);
    }