code: def to_json(self):
          
          json_dict = self.to_json_basic()
          json_dict['sub_1'] = self.sub_address_1
          json_dict['sub_2'] = self.sub_address_2
          json_dict['sub_3'] = self.sub_address_3
          json_dict['sub_4'] = self.sub_address_4
          return json.dumps(json_dict)
docs: :return: str