src/main/java/com/bazaarvoice/jless/parser/Parser.java
Rule FilterArgument() {
        return Sequence(
                Ident(), push(new FilterArgumentNode(match())), Ws0(),
                '=', Ws0(),
                Value(), peek(1).addChild(pop())
        );
    }
Rule FilterArgument() {
        return Sequence(
                Ident(), push(new FilterArgumentNode(match())), Ws0(),
                '=', Ws0(),
                Value(), peek(1).addChild(pop())
        );
    }
Ex: startColorstr=@lightColor