public function send(SenderManagerContract $sender)
    {
        $model = app('notifynder.resolver.model')->getModel(Notification::class);
        $table = (new $model())->getTable();

        $this->database->beginTransaction();
        $stackId = $this->database
                ->table($table)
                ->max('stack_id') + 1;
        foreach ($this->notifications as $key => $notification) {
            $this->notifications[$key] = $this->notifications[$key]->toDbArray();
            $this->notifications[$key]['stack_id'] = $stackId;
        }
        $insert = $this->database
            ->table($table)
            ->insert($this->notifications);
        $this->database->commit();

        return (bool) $insert;
    }