docs: def cache_key_prefix(request):
      """
      Cache key for yacms's cache middleware. Adds the current
      device and site ID.
      """
      cache_key = "%s.%s.%s." % (
          settings.CACHE_MIDDLEWARE_KEY_PREFIX,
          current_site_id(),
          device_from_request(request) or "default",
      )
      return _i18n_cache_key_suffix(request, cache_key)