code: function serveMagicLocale(request, response) {
      var default_locale_id = 'en-gb',
          found_locale, negotiator;
  
      if (!request.headers['accept-language']) {
          // No accept-language specified in the request so send the default
          found_locale = default_locale_id;
  
      } else {
          negotiator = new Negotiator(request);
          found_locale = negotiator.language(cached_available_locales);
  
          // If a locale couldn't be negotiated, use the default
          found_locale = found_locale || default_locale_id;
      }
  
      // Send a locale to the browser
      this.file_server.serveFile('/assets/locales/' + found_locale + '.json', 200, {
          Vary: 'Accept-Language',
          'Content-Language': found_locale
      }, request, response);
  }
docs: Handle the /assets/locales/magic.json request
  Find the closest translation we have for the language
  set in the browser.