docs: def set_device(request, device=""):
      """
      Sets a device name in a cookie when a user explicitly wants to go
      to the site for a particular device (eg mobile).
      """
      response = redirect(add_cache_bypass(next_url(request) or "/"))
      set_cookie(response, "yacms-device", device, 60 * 60 * 24 * 365)
      return response