code: func (rsc *ReplicaSetController) getPodReplicaSets(pod *v1.Pod) []*apps.ReplicaSet {
  	rss, err := rsc.rsLister.GetPodReplicaSets(pod)
  	if err != nil {
  		return nil
  	}
  	if len(rss) > 1 {
  		// ControllerRef will ensure we don't do anything crazy, but more than one
  		// item in this list nevertheless constitutes user error.
  		utilruntime.HandleError(fmt.Errorf("user error! more than one %v is selecting pods with labels: %+v", rsc.Kind, pod.Labels))
  	}
  	return rss
  }
docs: // getPodReplicaSets returns a list of ReplicaSets matching the given pod.