func (as *asciiSet) contains(c byte) bool {
	return (as[c/32] & (1 << (c % 32))) != 0
}

// containsRune is a simplified version of strings.ContainsRune
// to avoid importing the strings package.
// We avoid bytes.ContainsRune to avoid allocating a temporary copy of s.
func containsRune(s string, r rune) bool {
	for _, c := range s {
		if c == r {
			return true
		}
	}
	return false
}