code: func NewSelectorSpreadPriority(
  	serviceLister algorithm.ServiceLister,
  	controllerLister algorithm.ControllerLister,
  	replicaSetLister algorithm.ReplicaSetLister,
  	statefulSetLister algorithm.StatefulSetLister) (PriorityMapFunction, PriorityReduceFunction) {
  	selectorSpread := &SelectorSpread{
  		serviceLister:     serviceLister,
  		controllerLister:  controllerLister,
  		replicaSetLister:  replicaSetLister,
  		statefulSetLister: statefulSetLister,
  	}
  	return selectorSpread.CalculateSpreadPriorityMap, selectorSpread.CalculateSpreadPriorityReduce
  }
docs: // NewSelectorSpreadPriority creates a SelectorSpread.