code: func setupPubSub(c context.Context, baseURL, authServiceURL string) error {
  	pushURL := ""
  	if !info.IsDevAppServer(c) {
  		pushURL = baseURL + pubSubPushURLPath // push in prod, pull on dev server
  	}
  	service := getAuthService(c, authServiceURL)
  	return service.EnsureSubscription(c, subscriptionName(c, authServiceURL), pushURL)
  }
docs: // setupPubSub creates a subscription to AuthDB service notification stream.