func NewURLsValue(s string) *URLsValue {
	if s == "" {
		return &URLsValue{}
	}
	v := &URLsValue{}
	if err := v.Set(s); err != nil {
		plog.Panicf("new URLsValue should never fail: %v", err)
	}
	return v
}
func NewURLsValue(s string) *URLsValue {
	if s == "" {
		return &URLsValue{}
	}
	v := &URLsValue{}
	if err := v.Set(s); err != nil {
		plog.Panicf("new URLsValue should never fail: %v", err)
	}
	return v
}
// NewURLsValue implements "url.URL" slice as flag.Value interface.
// Given value is to be separated by comma.