if r1 == utf8.RuneError {
				return i
			}
			i += n
		}
		return -1
	case !utf8.ValidRune(r):
		return -1
	default:
		var b [utf8.UTFMax]byte
		n := utf8.EncodeRune(b[:], r)
		return Index(s, b[:n])
	}
}

// IndexAny interprets s as a sequence of UTF-8-encoded Unicode code points.
// It returns the byte index of the first occurrence in s of any of the Unicode