/**
  * Store a newly created resource in storage.
  *
  * @param Request $request
  * @param $cardNumber
  *
  * @return Response
  */
 public function store(Request $request, $cardNumber)
 {
     $this->validate($request, ['balance' => 'required|numeric|min:0']);
     $balance = $request->input('balance');
     $card = Card::firstOrCreate(['number' => $cardNumber]);
     $currentBalance = $card->addBalance($balance);
     if ($currentBalance->wasRecentlyCreated) {
         return $this->respondCreated(fractal()->item($currentBalance, new BalanceTransformer())->toArray());
     }
     return $this->respond(fractal()->item($currentBalance, new BalanceTransformer())->toArray());
 }