public static function getI18n(Translator $translator, $operator)
    {
        $ret = $operator;
        switch ($operator) {
            case self::INFERIOR:
                $ret = $translator->trans(
                    'Less than',
                    []
                );
                break;
            case self::INFERIOR_OR_EQUAL:
                $ret = $translator->trans(
                    'Less than or equals',
                    []
                );
                break;
            case self::EQUAL:
                $ret = $translator->trans(
                    'Equal to',
                    []
                );
                break;
            case self::SUPERIOR_OR_EQUAL:
                $ret = $translator->trans(
                    'Greater than or equals',
                    []
                );
                break;
            case self::SUPERIOR:
                $ret = $translator->trans(
                    'Greater than',
                    []
                );
                break;
            case self::DIFFERENT:
                $ret = $translator->trans(
                    'Not equal to',
                    []
                );
                break;
            case self::IN:
                $ret = $translator->trans(
                    'In',
                    []
                );
                break;
            case self::OUT:
                $ret = $translator->trans(
                    'Not in',
                    []
                );
                break;
            default:
        }

        return $ret;
    }