func (set TargetIDSet) add(targetID TargetID) {
	set[targetID] = struct{}{}
}

// Union - returns union with given set as new set.
func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {

func (set TargetIDSet) Union(sset TargetIDSet) TargetIDSet {
	nset := set.Clone()

	for k := range sset {
		nset.add(k)
	}

	return nset
}

// Difference - returns difference with given set as new set.
func (set TargetIDSet) Difference(sset TargetIDSet) TargetIDSet {
	nset := NewTargetIDSet()
	for k := range set {
		if _, ok := sset[k]; !ok {
			nset.add(k)
		}
	}

func (list *TargetList) Send(event Event, targetIDset TargetIDSet, sync bool) {
	if sync {
		list.sendSync(event, targetIDset)
	} else {
		list.sendAsync(event, targetIDset)
	}
}

func (list *TargetList) sendSync(event Event, targetIDset TargetIDSet) {
	var wg sync.WaitGroup
	for id := range targetIDset {
		target, ok := list.get(id)
		if !ok {
			continue
		}

			return true
		}
	}
	return false
}

// Match - returns TargetIDSet matching object name in rules.
func (rules Rules) Match(objectName string) TargetIDSet {
	targetIDs := NewTargetIDSet()

	for pattern, targetIDSet := range rules {
		if wildcard.MatchSimple(pattern, objectName) {
			targetIDs = targetIDs.Union(targetIDSet)
		}
	}

	return targetIDs
}

// Clone - returns copy of this rules.

	evnot.Lock()
	defer evnot.Unlock()

	targetIDSet := event.NewTargetIDSet()
	for k := range evnot.targetList.TargetMap() {
		targetIDSet[k] = struct{}{}
	}
	evnot.targetList.Remove(targetIDSet)
}

// Send - sends the event to all registered notification targets
func (evnot *EventNotifier) Send(args eventArgs) {
	evnot.RLock()

	Err error
}

// Remove - closes and removes targets by given target IDs.
func (list *TargetList) Remove(targetIDSet TargetIDSet) {
	list.Lock()
	defer list.Unlock()

	for id := range targetIDSet {
		target, ok := list.targets[id]
		if ok {
			target.Close()
			delete(list.targets, id)
		}
	}
}

// Targets - list all targets

	rulesMapCase4.add([]Name{ObjectCreatedAll}, "*", TargetID{"2", "amqp"})

	testCases := []struct {
		rulesMap       RulesMap
		eventName      Name
		objectName     string
		expectedResult TargetIDSet
	}{
		{rulesMapCase1, ObjectCreatedPut, "2010/photo.jpg", NewTargetIDSet()},
		{rulesMapCase2, ObjectCreatedPut, "2010/photo.jpg", NewTargetIDSet(TargetID{"1", "webhook"})},