code: func getIPSetVersionString(exec utilexec.Interface) (string, error) {
  	cmd := exec.Command(IPSetCmd, "--version")
  	cmd.SetStdin(bytes.NewReader([]byte{}))
  	bytes, err := cmd.CombinedOutput()
  	if err != nil {
  		return "", err
  	}
  	versionMatcher := regexp.MustCompile(VersionPattern)
  	match := versionMatcher.FindStringSubmatch(string(bytes))
  	if match == nil {
  		return "", fmt.Errorf("no ipset version found in string: %s", bytes)
  	}
  	return match[0], nil
  }
docs: // getIPSetVersionString runs "ipset --version" to get the version string
  // in the form of "X.Y", i.e "6.19"