code: func (kubemarkController *KubemarkController) GetNodeGroupSize(nodeGroup string) (int, error) {
  	selector := labels.SelectorFromSet(labels.Set(map[string]string{nodeGroupLabel: nodeGroup}))
  	nodes, err := kubemarkController.externalCluster.rcLister.List(selector)
  	if err != nil {
  		return 0, err
  	}
  	return len(nodes), nil
  }
docs: // GetNodeGroupSize returns the current size for the node group as observed.