for i := 0; i <= 64; i++ {
		x := uint64(5) << uint(i)
		if got := sys.TrailingZeros64(x); got != i {
			t.Errorf("TrailingZeros64(%d)=%d, want %d", x, got, i)
		}
	}
}
func TestTrailingZeros32(t *testing.T) {
	for i := 0; i <= 32; i++ {
		x := uint32(5) << uint(i)
		if got := sys.TrailingZeros32(x); got != i {
			t.Errorf("TrailingZeros32(%d)=%d, want %d", x, got, i)
		}
	}
}