code: func queryTime(query url.Values, name string, def time.Time) (time.Time, error) {
  	str := query.Get(name)
  	if str == "" {
  		return def, nil
  	}
  	parsed, err := time.Parse(time.RFC3339, str)
  	if err != nil {
  		return time.Time{}, trace.BadParameter("failed to parse %v as RFC3339 time: %v", name, str)
  	}
  	return parsed, nil
  }
docs: // queryTime parses the query string parameter with the specified name as a
  // RFC3339 time and returns it.
  //
  // If there's no such parameter, specified default value is returned.