protected function _parseRange($value)
    {
        if (strpos($value, '..') !== false) {
            list($lower, $upper) = explode('..', $value);
        } else {
            $lower = $upper = $value;
        }

        if (intval($lower) > intval($upper)) {
            list($lower, $upper) = [$upper, $lower];
        }

        return [
            'lower' => $lower,
            'upper' => $upper,
        ];
    }