code: func parseSubnetKey(s string) (ip.IP4Net, error) {
  	if parts := subnetRegex.FindStringSubmatch(s); len(parts) == 3 {
  		snIp := net.ParseIP(parts[1]).To4()
  		prefixLen, err := strconv.ParseUint(parts[2], 10, 5)
  		if snIp != nil && err == nil {
  			return ip.IP4Net{IP: ip.FromIP(snIp), PrefixLen: uint(prefixLen)}, nil
  		}
  	}
  
  	return ip.IP4Net{}, errors.New("Error parsing IP Subnet")
  }
docs: /// Implementation