func ContainsFunc(b []byte, f func(rune) bool) bool {
	return IndexFunc(b, f) >= 0
}

// IndexByte returns the index of the first instance of c in b, or -1 if c is not present in b.
func IndexByte(b []byte, c byte) int {
	return bytealg.IndexByte(b, c)
}

func indexBytePortable(s []byte, c byte) int {
	for i, b := range s {
		if b == c {
			return i
		}
	}
	return -1