code: func sortPodsByQOS(preemptor *v1.Pod, pods []*v1.Pod) (bestEffort, burstable, guaranteed []*v1.Pod) {
  	for _, pod := range pods {
  		if kubetypes.Preemptable(preemptor, pod) {
  			switch v1qos.GetPodQOS(pod) {
  			case v1.PodQOSBestEffort:
  				bestEffort = append(bestEffort, pod)
  			case v1.PodQOSBurstable:
  				burstable = append(burstable, pod)
  			case v1.PodQOSGuaranteed:
  				guaranteed = append(guaranteed, pod)
  			default:
  			}
  		}
  	}
  
  	return
  }
docs: // sortPodsByQOS returns lists containing besteffort, burstable, and guaranteed pods that
  // can be preempted by preemptor pod.