if(context != null)
if(context != null) {
    public Value eval(DocumentSet docs, NodeSet context, NodeProxy node) {        if(getLength() == 0)            return new ValueNodeSet(context);        NodeSet rr, rl = (NodeSet)getExpression(0).eval(docs, context, null).getNodeList();        if(context != null)            rl = getParents(rl, context);        for(int i = 1; i < getLength(); i++) {            rr = (NodeSet)getExpression(i).eval(docs, context, null).getNodeList();            if(context != null)                rr = getParents(rr, context);            rl = rl.union(rr);        }        return new ValueNodeSet(rl);    }