code: func fakeClusterID(clusterID string) ClusterID {
  	return ClusterID{
  		clusterID: &clusterID,
  		store: cache.NewStore(func(obj interface{}) (string, error) {
  			return "", nil
  		}),
  	}
  }
docs: // Stubs ClusterID so that ClusterID.getOrInitialize() does not require calling
  // gce.Initialize()