private function notify(callable $notifier = null, $type, $data = null)
    {
        if (null !== $notifier) {
            return $notifier($type, $data);
        }
    }
private function notify(callable $notifier = null, $type, $data = null)
    {
        if (null !== $notifier) {
            return $notifier($type, $data);
        }
    }
@param callable|null $notifier
@param string        $type
@param mixed         $data

@return mixed