// Send - sends events to targets identified by target IDs.
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