code: func (d *Driver) Cleanup() error {
  	err := d.DeviceSet.Shutdown(d.home)
  	umountErr := mount.RecursiveUnmount(d.home)
  
  	// in case we have two errors, prefer the one from Shutdown()
  	if err != nil {
  		return err
  	}
  
  	return umountErr
  }
docs: // Cleanup unmounts a device.