fmt.Fprintf(os.Stderr, "usage: go run mkzip.go zoneinfo.zip\n")
	os.Exit(2)
}

func main() {
	log.SetPrefix("mkzip: ")
	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()
	args := flag.Args()
	if len(args) != 1 || !strings.HasSuffix(args[0], ".zip") {
		usage()
	}

	var zb bytes.Buffer
	zw := zip.NewWriter(&zb)
	seen := make(map[string]bool)