code: func listingPage(q url.Values) (start string, limit int) {
  	// if limit is not a valid integer (or blank string),
  	// ignore the error and use the returned 0 value
  	limit, _ = strconv.Atoi(q.Get("limit"))
  	return q.Get("start"), limit
  }
docs: // listingPage returns start value and listing limit
  // from url query values.