code: func parseXlog(x xlog.Position) (pos int64, err error) {
  	if x == "" {
  		return 0, nil
  	}
  	pos, err = strconv.ParseInt(string(x), 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.