public function processUserPayment($userName)
 {
     $user = new User($userName);
     $paymentMethod = $user->getPaymentMethod();
     $this->executePayment($paymentMethod);
 }
 function processUserPayment(User $user)
 {
     $paymentMethod = $user->getPaymentMethod();
     $this->executePayment($paymentMethod);
 }