public function registerSenders()
    {
        app('notifynder')->extend('sendSingle', function (array $notifications) {
            return new SingleSender($notifications);
        });

        app('notifynder')->extend('sendMultiple', function (array $notifications) {
            return new MultipleSender($notifications);
        });

        app('notifynder')->extend('sendOnce', function (array $notifications) {
            return new OnceSender($notifications);
        });
    }