public static function numberBetween($val, $min, $max, $opt = 'II')
    {
        switch ($opt) {
            case 'EE':
                return ($val > $min && $val < $max);
                break;
            case 'EI':
                return ($val > $min && $val <= $max);
                break;
            case 'IE':
                return ($val >= $min && $val < $max);
                break;
            case 'II':
            default:
                return ($val >= $min && $val <= $max);
        }
    }