code: func (l *WAL) ClosedSegments() ([]string, error) {
  	l.mu.RLock()
  	defer l.mu.RUnlock()
  	// Not loading files from disk so nothing to do
  	if l.path == "" {
  		return nil, nil
  	}
  
  	var currentFile string
  	if l.currentSegmentWriter != nil {
  		currentFile = l.currentSegmentWriter.path()
  	}
  
  	files, err := segmentFileNames(l.path)
  	if err != nil {
  		return nil, err
  	}
  
  	var closedFiles []string
  	for _, fn := range files {
  		// Skip the current path
  		if fn == currentFile {
  			continue
  		}
  
  		closedFiles = append(closedFiles, fn)
  	}
  
  	return closedFiles, nil
  }
docs: // ClosedSegments returns a slice of the names of the closed segment files.