public function getSortedValues($order = 'asc')
    {
        $values = $this->values->toArray();
        usort($values, function ($a, $b) use ($order) {
            $left = $a->getAttribute()->getSort();
            $right = $b->getAttribute()->getSort();

            if ($order == 'desc') {
                return ($left < $right) ? 1 : -1;
            }

            return ($left > $right) ? 1 : -1;
        });

        return $values;
    }