protected function getSforVariables(\Twig_TokenStream $stream)
    {
        $forOptions = new \Twig_Node_Expression_Array([], $stream->getCurrent()->getLine());
        $this->addKeyValues($stream, $forOptions);
        $sfor = $forOptions->getNode(1)->getAttribute('value');

        preg_match('/([\w\d\_]+) in ([\w\d\_\.\(\)\'\"]+)/', $sfor, $matches);

        if (!isset($matches[1]) || !isset($matches[2])) {
            throw new \Twig_Error_Syntax("The sfor parameter must be the pattern: '<variable> in <variables>'", $stream->getCurrent()->getLine(), $stream->getSourceContext()->getName());
        }

        return [$matches[1], $this->getSforInVariableNode($matches[2])];
    }