code: func (ssc *StatefulSetController) getStatefulSetsForPod(pod *v1.Pod) []*apps.StatefulSet {
  	sets, err := ssc.setLister.GetPodStatefulSets(pod)
  	if err != nil {
  		return nil
  	}
  	// More than one set is selecting the same Pod
  	if len(sets) > 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 StatefulSet is selecting pods with labels: %+v",
  				pod.Labels))
  	}
  	return sets
  }
docs: // getStatefulSetsForPod returns a list of StatefulSets that potentially match
  // a given pod.