/**
  * Bootstrap the application services.
  *
  * @return void
  */
 public function boot()
 {
     Transaction::saving(function ($trans) {
         $user = User::find($trans->user_id);
         if ($user->balance < -$trans->amount) {
             return false;
         } else {
             $trans->running = $user->balance + $trans->amount;
         }
     });
     Transaction::saved(function ($trans) {
         $user = User::find($trans->user_id);
         $user->balance = $user->balance + $trans->amount;
         $user->save();
     });
 }