code: func MachineID(root string) string {
  	fullPath := filepath.Join(root, "/etc/machine-id")
  	id, err := ioutil.ReadFile(fullPath)
  	if err != nil {
  		return ""
  	}
  	return strings.TrimSpace(string(id))
  }
docs: // MachineID returns the uuid specified `/etc/machine-id`
  // it first prepends the provided root to the filepath
  // if there is an error reading the file it returns the empty string