code: func (mounter *Mounter) Unmount(target string) error {
  	klog.V(4).Infof("Unmounting %s", target)
  	command := exec.Command("umount", target)
  	output, err := command.CombinedOutput()
  	if err != nil {
  		return fmt.Errorf("Unmount failed: %v\nUnmounting arguments: %s\nOutput: %s\n", err, target, string(output))
  	}
  	return nil
  }
docs: // Unmount unmounts the target.