// IPv6 addresses.
func (ip Addr) Is6() bool {
	return ip.z != z0 && ip.z != z4
}

// Unmap returns ip with any IPv4-mapped IPv6 address prefix removed.
//
// That is, if ip is an IPv6 address wrapping an IPv4 address, it
// returns the wrapped IPv4 address. Otherwise it returns ip unmodified.
func (ip Addr) Unmap() Addr {
	if ip.Is4In6() {
		ip.z = z4
	}
	return ip
}