func UniqueStringsMapFromFlag(fs *flag.FlagSet, flagName string) map[string]struct{} {
	return (*fs.Lookup(flagName).Value.(*UniqueStringsValue)).Values
}
func UniqueStringsMapFromFlag(fs *flag.FlagSet, flagName string) map[string]struct{} {
	return (*fs.Lookup(flagName).Value.(*UniqueStringsValue)).Values
}
// UniqueStringsMapFromFlag returns a map of strings from the flag.