code: def payload(self):
          
          if self._content_type is not None:
              try:
                  return self._payload[self._content_type]
              except KeyError:
                  raise KeyError("Content-Type not available")
          else:
  
              if defines.Content_types["text/plain"] in self._payload:
                  return self._payload[defines.Content_types["text/plain"]]
              else:
                  val = list(self._payload.keys())
                  return val[0], self._payload[val[0]]
docs: Get the payload of the resource according to the content type specified by required_content_type or
          "text/plain" by default.
  
          :return: the payload.