func toPackageName(version string) string {
	if version == "unversioned" {
		return "v0"
	}
	parts := strings.Split(version, ".")
	i := 1
	p := parts[len(parts)-i]
	for p == "0" && i <= len(parts) {
		i++
		p = parts[len(parts)-i]
	}
	version = strings.Join(parts, "_")
	return fmt.Sprintf("v%s", version)
}
func toPackageName(version string) string {
	if version == "unversioned" {
		return "v0"
	}
	parts := strings.Split(version, ".")
	i := 1
	p := parts[len(parts)-i]
	for p == "0" && i <= len(parts) {
		i++
		p = parts[len(parts)-i]
	}
	version = strings.Join(parts, "_")
	return fmt.Sprintf("v%s", version)
}
// Convert version number in index.json to go package name
// "1.6" => "v1_6"