code: func defaultUserName() string {
  	userName := os.Getenv("USER")
  	if userName == "" {
  		userName = os.Getenv("USERNAME")
  	}
  	if userName == "" {
  		userName = fmt.Sprintf("user%d", os.Getuid())
  	}
  	return userName
  }
docs: ////////////////////////////////////////////////////////////////////////////////
  // Private
  ////////////////////////////////////////////////////////////////////////////////
  // If the platform specific implementation of user.Current()
  // isn't available, go get something that's a "stable" user
  // name