docs: def create_subscription(self, *, customer_id, credit_card_token, plan_code, quantity=None, installments=None,
                              trial_days=None, immediate_payment=None, extra1=None, extra2=None, delivery_address=None,
                              notify_url=None, recurring_bill_items=None):
          """
          Creating a new subscription of a client to a plan.
  
          Args:
              customer_id: Customer that will be associated to the subscription.
              You can find more information in the "Customer" section of this page.
  
              credit_card_token: Customer's credit card that is selected to make the payment.
              You can find more information in the "Credit card" section of this page.
  
              plan_code: Plan that will be associated to the subscription.
              You can find more information in the "Plan" section of this page.
  
              quantity: Total amount of plans that will be acquired with the subscription.
              Numeric.
  
              installments: Total amount of installments to defer the payment.
              Numeric.
  
              trial_days: Total amount of trial days of the subscription.
              This variable has preference over the plan's trial days.
              Numeric.
  
              immediate_payment:
  
              extra1:
  
              extra2:
  
              delivery_address:
  
              notify_url:
  
              recurring_bill_items:
  
          Returns:
  
          """
          payload = {
              "quantity": quantity,
              "installments": installments,
              "trialDays": trial_days,
              "immediatePayment": immediate_payment,
              "extra1": extra1,
              "extra2": extra2,
              "customer": {
                  "id": customer_id,
                  "creditCards": [
                      {
                          "token": credit_card_token
                      }
                  ]
              },
              "plan": {
                  "planCode": plan_code
              },
              "deliveryAddress": delivery_address,
              "notifyUrl": notify_url,
              "recurringBillItems": recurring_bill_items
          }
          return self.client._post(self.url + 'subscriptions', json=payload, headers=self.get_headers())