code: func Dec(IP net.IP) net.IP {
  	IP = checkIPv4(IP)
  	decIP := make([]byte, len(IP))
  	copy(decIP, IP)
  	decIP = checkIPv4(decIP)
  	for j := len(decIP) - 1; j >= 0; j-- {
  		decIP[j]--
  		if decIP[j] < 255 {
  			break
  		}
  	}
  	return decIP
  }
docs: //Dec decreases the IP by one this returns a new []byte for the IP