code: func subscriptionName(c context.Context, authServiceURL string) string {
  	subIDPrefix := "gae-v1"
  	if info.IsDevAppServer(c) {
  		subIDPrefix = "dev-app-server-v1"
  	}
  	serviceURL, err := url.Parse(authServiceURL)
  	if err != nil {
  		panic(err)
  	}
  	return fmt.Sprintf("projects/%s/subscriptions/%s+%s", info.AppID(c), subIDPrefix, serviceURL.Host)
  }
docs: // subscriptionName returns full PubSub subscription name for AuthDB
  // change notifications stream from given auth service.