code: def withdraw(self, amount, currency, payment_method_id):
          
          params = {'amount': amount,
                    'currency': currency,
                    'payment_method_id': payment_method_id}
          return self._send_message('post', '/withdrawals/payment-method',
                                    data=json.dumps(params))
docs: Withdraw funds to a payment method.
  
          See AuthenticatedClient.get_payment_methods() to receive
          information regarding payment methods.
  
          Args:
              amount (Decimal): The amount to withdraw.
              currency (str): Currency type (eg. 'BTC')
              payment_method_id (str): ID of the payment method.
  
          Returns:
              dict: Withdraw details. Example::
                  {
                      "id":"593533d2-ff31-46e0-b22e-ca754147a96a",
                      "amount": "10.00",
                      "currency": "USD",
                      "payout_at": "2016-08-20T00:31:09Z"
                  }