code: func (i *Index) loadMeta() error {
  	var pb internal.IndexMeta
  
  	// Read data from meta file.
  	buf, err := ioutil.ReadFile(filepath.Join(i.path, ".meta"))
  	if os.IsNotExist(err) {
  		return nil
  	} else if err != nil {
  		return errors.Wrap(err, "reading")
  	} else {
  		if err := proto.Unmarshal(buf, &pb); err != nil {
  			return errors.Wrap(err, "unmarshalling")
  		}
  	}
  
  	// Copy metadata fields.
  	i.keys = pb.Keys
  	i.trackExistence = pb.TrackExistence
  
  	return nil
  }
docs: // loadMeta reads meta data for the index, if any.