code: func GetCgroupPathByPid(pid int, controller string) (string, error) {
  	parts, err := parseCgroupController(fmt.Sprintf("/proc/%d/cgroup", pid), controller)
  	if err != nil {
  		return "", err
  	}
  	return parts[2], nil
  }
docs: // GetCgroupPathByPid returns the cgroup path of the process with the given pid
  // and given controller.