// AppendRange should collapse each of the new ranges
	// into the earlier ones (it looks back two ranges), so that
	// the slice never grows very large.
	// Note that we are not calling cleanClass.
	var r []rune
	for i := rune('A'); i <= 'Z'; i++ {
		r = appendRange(r, i, i)
		r = appendRange(r, i+'a'-'A', i+'a'-'A')
	}
	if string(r) != "AZaz" {