stddev := math.Sqrt(variance)
	if math.Abs(float64(cnt1-mean)) > 10*stddev {
		t.Errorf("unfair select: in %d trials, results were %d, %d", trials, cnt1, cnt2)
	}
	close(done)
	wg.Wait()
}

func TestChanSendInterface(t *testing.T) {
	type mt struct{}
	m := &mt{}
	c := make(chan any, 1)
	c <- m
	select {
	case c <- m:
	default:
	}
	select {
	case c <- m:
	case c <- &mt{}:
	default:
	}