func URLsFromFlag(fs *flag.FlagSet, urlsFlagName string) []url.URL {
	return []url.URL(*fs.Lookup(urlsFlagName).Value.(*URLsValue))
}
func URLsFromFlag(fs *flag.FlagSet, urlsFlagName string) []url.URL {
	return []url.URL(*fs.Lookup(urlsFlagName).Value.(*URLsValue))
}
// URLsFromFlag returns a slices from url got from the flag.