code: func RegisterMandatoryFitPredicate(name string, predicate predicates.FitPredicate) string {
  	schedulerFactoryMutex.Lock()
  	defer schedulerFactoryMutex.Unlock()
  	validateAlgorithmNameOrDie(name)
  	fitPredicateMap[name] = func(PluginFactoryArgs) predicates.FitPredicate { return predicate }
  	mandatoryFitPredicates.Insert(name)
  	return name
  }
docs: // RegisterMandatoryFitPredicate registers a fit predicate with the algorithm registry, the predicate is used by
  // kubelet, DaemonSet; it is always included in configuration. Returns the name with which the predicate was
  // registered.