code: func PickInstallMode(im InstallMode) (InstallMode, error) {
  	switch {
  	case runtime.GOOS == "windows":
  		return InstallModeCopy, nil // Windows supports only 'copy' mode
  	case im == "":
  		return InstallModeSymlink, nil // default on other platforms
  	}
  	if err := ValidateInstallMode(im); err != nil {
  		return "", err
  	}
  	return im, nil
  }
docs: // PickInstallMode validates the install mode and picks the correct default
  // for the platform if no install mode is given.