code: func setDefaultUmask() error {
  	desiredUmask := 0022
  	unix.Umask(desiredUmask)
  	if umask := unix.Umask(desiredUmask); umask != desiredUmask {
  		return fmt.Errorf("failed to set umask: expected %#o, got %#o", desiredUmask, umask)
  	}
  
  	return nil
  }
docs: // setDefaultUmask sets the umask to 0022 to avoid problems
  // caused by custom umask