code: func parseDuration(lease string) time.Duration {
  	dur, err := time.ParseDuration(lease)
  	if err != nil {
  		dur, err = time.ParseDuration(lease + "s")
  	}
  	if err != nil || dur < 0 {
  		log.Fatal("invalid lease duration", zap.String("lease", lease))
  	}
  	return dur
  }
docs: // parseDuration parses lease argument string.