Inheritance: extends Illuminate\Foundation\Http\FormRequest
 public function postPaymentOption(PaymentOptionRequest $request)
 {
     $orderData = Session::get('order_data');
     $cartProducts = Session::get('cart');
     $paymentMethod = Payment::get($request->get('payment_option'));
     $redirectUrl = $paymentMethod->process($orderData, $cartProducts);
     $orderData['payment_method'] = $request->get('payment_option');
     Session::put('order_data', $orderData);
     if (null === $redirectUrl) {
         return redirect()->route('checkout.step.review');
     } else {
         return Redirect::to($redirectUrl);
     }
 }