code: def put_http_meta(self, key, value):
          
          self._check_ended()
  
          if value is None:
              return
  
          if key == http.STATUS:
              if isinstance(value, string_types):
                  value = int(value)
              self.apply_status_code(value)
  
          if key in http.request_keys:
              if 'request' not in self.http:
                  self.http['request'] = {}
              self.http['request'][key] = value
          elif key in http.response_keys:
              if 'response' not in self.http:
                  self.http['response'] = {}
              self.http['response'][key] = value
          else:
              log.warning("ignoring unsupported key %s in http meta.", key)
docs: Add http related metadata.
  
          :param str key: Currently supported keys are:
              * url
              * method
              * user_agent
              * client_ip
              * status
              * content_length
          :param value: status and content_length are int and for other
              supported keys string should be used.