private function pushStack($iterable)
    {
        $iterator = $this->getIterator($iterable);
        $isObject = $this->isObject($iterable, $iterator);

        if ($isObject) {
            $this->outputLine('{', JsonToken::T_LEFT_BRACE);
        } else {
            $this->outputLine('[', JsonToken::T_LEFT_BRACKET);
        }

        $this->first = true;
        $this->stack[] = $iterator;
        $this->stackType[] = $isObject;
    }