expectValue: types.OptionalNone,
		},
		{
			name:        "dns1123Label",
			expr:        `format.dns1123Label().validate("contains a space")`,

	if !ok {
		return types.MaybeNoSuchOverloadErr(arg2)
	}

	res := f.ValidateFunc(str)
	if len(res) == 0 {
		return types.OptionalNone
	}
	return types.OptionalOf(types.NewStringList(types.DefaultTypeAdapter, res))