code: func (d *DataDirectory) IsEmpty() (bool, error) {
  	dir, err := os.Open(d.path)
  	if err != nil {
  		return false, fmt.Errorf("failed to open data directory %s: %v", d.path, err)
  	}
  	defer dir.Close()
  	_, err = dir.Readdirnames(1)
  	if err == io.EOF {
  		return true, nil
  	}
  	return false, err
  }
docs: // IsEmpty returns true if the data directory is entirely empty.