duration.go
func IsDuration(str string) bool {
	_, err := ParseDuration(str)
	return err == nil
}
func IsDuration(str string) bool {
	_, err := ParseDuration(str)
	return err == nil
}
func IsDuration ( str string ) bool { _ , err := ParseDuration ( str ) return err == nil }
// IsDuration returns true if the provided string is a valid duration
IsDuration returns true if the provided string is a valid duration