public static Set<Element> execute(String query, Element rootElement) throws InvalidQueryException {
        Set<Element> interviewed = new TreeSet<>();
        Set<Element> output = new TreeSet<>();
        interviewed.add(rootElement);
        interviewed.addAll(rootElement.getAllDescendants());

        QueryParserImpl selectors = new QueryParserImpl(query);
        Set<Element> outputOfPreviousSelector = new TreeSet<>();
        int i = 0;
        while (selectors.hasNextSelector()) {
            output.addAll(selectors.getNextSelector().apply(outputOfPreviousSelector)); //ono to nepozna ktere apply ma pouzit
            outputOfPreviousSelector = selectors.getNextSelector().apply(outputOfPreviousSelector);
        }
        return output;
    }
}