internal/api.go
func DefaultTicket() string {
	defaultTicketOnce.Do(func() {
		if IsDevAppServer() {
			defaultTicket = "testapp" + defaultTicketSuffix
			return
		}
		appID := partitionlessAppID()
		escAppID := strings.Replace(strings.Replace(appID, ":", "_", -1), ".", "_", -1)
		majVersion := VersionID(nil)
		if i := strings.Index(majVersion, "."); i > 0 {
			majVersion = majVersion[:i]
		}
		defaultTicket = fmt.Sprintf("%s/%s.%s.%s", escAppID, ModuleName(nil), majVersion, InstanceID())
	})
	return defaultTicket
}
func DefaultTicket() string {
	defaultTicketOnce.Do(func() {
		if IsDevAppServer() {
			defaultTicket = "testapp" + defaultTicketSuffix
			return
		}
		appID := partitionlessAppID()
		escAppID := strings.Replace(strings.Replace(appID, ":", "_", -1), ".", "_", -1)
		majVersion := VersionID(nil)
		if i := strings.Index(majVersion, "."); i > 0 {
			majVersion = majVersion[:i]
		}
		defaultTicket = fmt.Sprintf("%s/%s.%s.%s", escAppID, ModuleName(nil), majVersion, InstanceID())
	})
	return defaultTicket
}
// DefaultTicket returns a ticket used for background context or dev_appserver.