code: func GetThisCgroupDir(subsystem string) (string, error) {
  	f, err := os.Open("/proc/self/cgroup")
  	if err != nil {
  		return "", err
  	}
  	defer f.Close()
  
  	return ParseCgroupFile(subsystem, f)
  }
docs: // Returns the relative path to the cgroup docker is running in.