docs: def _log_function(self, handler):
          """Override Application.log_function so that what to log can be controlled.
          """
          if handler.get_status() < 400:
              log_method = request_log.info
          elif handler.get_status() < 500:
              log_method = request_log.warning
          else:
              log_method = request_log.error
          for i in settings['LOGGING_IGNORE_URLS']:
              if handler.request.uri.startswith(i):
                  log_method = request_log.debug
                  break
  
          request_time = 1000.0 * handler.request.request_time()
          log_method("%d %s %.2fms", handler.get_status(),
                     handler._request_summary(), request_time)