Leafo\ScssPhp\Compiler::listSeparatorForJoin PHP Method

    protected function listSeparatorForJoin($list1, $sep)
    {
        if (!isset($sep)) {
            return $list1[1];
        }
        switch ($this->compileValue($sep)) {
            case 'comma':
                return ',';
            case 'space':
                return '';
            default:
                return $list1[1];
        }
    }