defer after.Stop()
	send := func(v int) {
		select {
		case c <- v:
		case <-after.C:
			panic("timed out sending to Sink")
		}
	}
	send(1)
	send(2)
	send(3)
	close(c)
}

func TestExclusive() {
	val := 0
	ex := a.MakeExclusive(&val)

	var wg sync.WaitGroup
	f := func() {
		defer wg.Done()
		for i := 0; i < 10; i++ {
			p := ex.Acquire()
			(*p)++
			ex.Release(p)
		}
	}

	send := func(v int) {
		select {
		case c <- v:
		case <-after.C:
			panic("timed out sending to _Sink")
		}
	}
	send(1)
	send(2)
	send(3)
	close(c)
}

func TestExclusive() {
	val := 0
	ex := _MakeExclusive(&val)

	var wg sync.WaitGroup
	f := func() {
		defer wg.Done()
		for i := 0; i < 10; i++ {
			p := ex.Acquire()
			(*p)++
			ex.Release(p)
		}
	}