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