code: def method(self, quote_id, payment_data, store_view=None):
          
          return bool(
              self.call('cart_payment.method',
                  [quote_id, payment_data, store_view])
          )
docs: Allows you to set a payment method for a shopping cart (quote).
  
          :param quote_id: Shopping cart ID (quote ID)
          :param payment_data, dict of payment details, example
              {
                  'po_number': '',
                  'method': 'checkmo',
                  'cc_cid': '',
                  'cc_owner': '',
                  'cc_number': '',
                  'cc_type': '',
                  'cc_exp_year': '',
                  'cc_exp_month': ''
              }
          :param store_view: Store view ID or code
          :return: boolean, True on success