code: func segmentFileNames(dir string) ([]string, error) {
  	names, err := filepath.Glob(filepath.Join(dir, fmt.Sprintf("%s*.%s", WALFilePrefix, WALFileExtension)))
  	if err != nil {
  		return nil, err
  	}
  	sort.Strings(names)
  	return names, nil
  }
docs: // segmentFileNames will return all files that are WAL segment files in sorted order by ascending ID.