def log_request(self, handler: RequestHandler) -> None:
        """Writes a completed HTTP request to the logs.

        By default writes to the python root logger.  To change
        this behavior either subclass Application and override this method,
        or pass a function in the application settings dictionary as
        ``log_function``.
        """
        if "log_function" in self.settings:
            self.settings["log_function"](handler)
            return
        if handler.get_status() < 400:
            log_method = access_log.info
        elif handler.get_status() < 500:
            log_method = access_log.warning
        else:
            log_method = access_log.error
        request_time = 1000.0 * handler.request.request_time()
        log_method(
            "%d %s %.2fms",
            handler.get_status(),
            handler._request_summary(),
            request_time,
        )