code: func (p *playground) Cleanup() error {
  	if err := os.Remove(p.playground); err != nil {
  		return err
  	}
  
  	if err := p.mnt.Unmount(p.tmpDir, 0); err != nil {
  		return err
  	}
  
  	return os.Remove(p.tmpDir)
  }
docs: // Cleanup cleans up the playground.
  // It removes it, unmounts the parent directory, and removes the unmounted directory.