return bytealg.LastIndexByte(s, c)
}

// IndexRune interprets s as a sequence of UTF-8-encoded code points.
// It returns the byte index of the first occurrence in s of the given rune.
// It returns -1 if rune is not present in s.
// If r is utf8.RuneError, it returns the first instance of any
// invalid UTF-8 byte sequence.
func IndexRune(s []byte, r rune) int {
	switch {
	case 0 <= r && r < utf8.RuneSelf: