code: def log_request(self, handler):
          
          if config.LOG_FUNCTION in self.settings:
              self.settings[config.LOG_FUNCTION](handler)
              return
          if handler.get_status() < 400:
              log_method = LOGGER.info
          elif handler.get_status() < 500:
              log_method = LOGGER.warning
          else:
              log_method = LOGGER.exception
          request_time = 1000.0 * handler.request.request_time()
          log_method("%d %s %.2fms", handler.get_status(),
                     handler._request_summary(), request_time)
docs: Writes a completed HTTP request to the logs.
  
          By default writes to the tinman.application LOGGER.  To change
          this behavior either subclass Application and override this method,
          or pass a function in the application settings dictionary as
          'log_function'.
  
          :param tornado.web.RequestHandler handler: The request handler