code: func passphraseFetcher(name string) ([]byte, error) {
  	var passphrase = settings.HelmKeyPassphrase()
  	if passphrase != "" {
  		return []byte(passphrase), nil
  	}
  
  	fmt.Printf("Password for key %q >  ", name)
  	pw, err := terminal.ReadPassword(int(syscall.Stdin))
  	fmt.Println()
  	return pw, err
  }
docs: // passphraseFetcher implements provenance.PassphraseFetcher