src/main/java/com/bazaarvoice/jless/parser/Parser.java
@MemoMismatches
    Rule SelectorGroup() {
        return Sequence(
                Selector(), push(new SelectorGroupNode(pop())), Ws0Nodes(),
                ZeroOrMore(
                        ',', Ws0Nodes(),
                        Selector(), peek(1).addChild(pop())
                ),
                Ws0Nodes()
        );
    }
@MemoMismatches
    Rule SelectorGroup() {
        return Sequence(
                Selector(), push(new SelectorGroupNode(pop())), Ws0Nodes(),
                ZeroOrMore(
                        ',', Ws0Nodes(),
                        Selector(), peek(1).addChild(pop())
                ),
                Ws0Nodes()
        );
    }
Selector Ws0 (',' Ws0 Selector)* Ws0