src/main/java/br/com/starcode/parccser/Parser.java
protected List<Selector> groups() throws ParserException {

        List<Selector> groups = new ArrayList<Selector>();
        int groupNumber = 0;
        while (!end()) {
            ignoreWhitespaces();
            parserListener.beginGroup(groupNumber, pos);
            Selector selector = selector();
            groups.add(selector);
            parserListener.endGroup(selector);
            groupNumber++;
            ignoreWhitespaces();
            if (!end() && current != ',') {
                throw new ParserException("There is something left in the selector at position " + pos);
            }
            next();
        }
        return groups;

    }
protected List<Selector> groups() throws ParserException {

        List<Selector> groups = new ArrayList<Selector>();
        int groupNumber = 0;
        while (!end()) {
            ignoreWhitespaces();
            parserListener.beginGroup(groupNumber, pos);
            Selector selector = selector();
            groups.add(selector);
            parserListener.endGroup(selector);
            groupNumber++;
            ignoreWhitespaces();
            if (!end() && current != ',') {
                throw new ParserException("There is something left in the selector at position " + pos);
            }
            next();
        }
        return groups;

    }
selectors_group
: selector [ COMMA S* selector ]*