or.go

var Or func(channels ...<-chan interface{}) <-chan interface{}

func init() {
	Or = func(channels ...<-chan interface{}) <-chan interface{} {
		switch len(channels) {
		case 0:
			return nil
		case 1:
			return channels[0]
		}

		orDone := make(chan interface{})
		go func() {
			defer close(orDone)

			switch len(channels) {
			case 2:
				select {
				case <-channels[0]:
				case <-channels[1]:
				}
			default:
				select {
				case <-channels[0]:
				case <-channels[1]:
				case <-channels[2]:
				case <-Or(append(channels[3:], orDone)...):
				}
			}
		}()
		return orDone
	}
}
  
sig := func(after time.Duration) <-chan interface{} {
	c := make(chan interface{})
	go func() {
		defer close(c)
		time.Sleep(after)
	}()
	return c
}
start := time.Now()
<-Or(
	sig(10*time.Second),
	sig(5*time.Second),
	sig(1*time.Second),
)
tm := time.Since(start)
if tm > 2*time.Second || tm < time.Second {
	t.Error(`error`)
}

race fn Or