code: func parseXlog(x xlog.Position) (pos int64, err error) {
  	if x == "" {
  		return 0, nil
  	}
  	parts := strings.SplitN(string(x), "-", 3)
  	if len(parts) != 3 {
  		err = fmt.Errorf("malformed xlog position %q", x)
  		return
  	}
  
  	pos, err = strconv.ParseInt(parts[2], 10, 64)
  	if err != nil {
  		return 0, err
  	}
  
  	return pos, err
  }
docs: // parseXlog parses a string xlog position into an int64
  // Returns an error if the xlog position is not formatted correctly.