func (n NetworkNumber) ToIP() net.IP {
	ip := make(net.IP, len(n)*BytePerUint32)
	for i := 0; i < len(n); i++ {
		idx := i * net.IPv4len
		binary.BigEndian.PutUint32(ip[idx:idx+net.IPv4len], n[i])
	}
	if len(ip) == net.IPv4len {
		ip = net.IPv4(ip[0], ip[1], ip[2], ip[3])
	}
	return ip
}
func (n NetworkNumber) ToIP() net.IP {
	ip := make(net.IP, len(n)*BytePerUint32)
	for i := 0; i < len(n); i++ {
		idx := i * net.IPv4len
		binary.BigEndian.PutUint32(ip[idx:idx+net.IPv4len], n[i])
	}
	if len(ip) == net.IPv4len {
		ip = net.IPv4(ip[0], ip[1], ip[2], ip[3])
	}
	return ip
}
// ToIP returns equivalent net.IP.