code: def _generate_combined_log(self, request, response):
          
          current_time = datetime.utcnow()
          data_len = '-' if response.data is None else len(response.data)
          return '{0} - - [{1}] {2} {3} {4} {5} {6}'.format(request.remote_addr, current_time, request.method,
                                                          request.relative_uri, response.status,
                                                          data_len, request.user_agent)
docs: Given a request/response pair, generate a logging format similar to the NGINX combined style.