code: def _is_json_serialized_jws(self, json_jws):
          
          json_ser_keys = {"payload", "signatures"}
          flattened_json_ser_keys = {"payload", "signature"}
          if not json_ser_keys.issubset(
                  json_jws.keys()) and not flattened_json_ser_keys.issubset(
                  json_jws.keys()):
              return False
          return True
docs: Check if we've got a JSON serialized signed JWT.
  
          :param json_jws: The message
          :return: True/False