if (e.isBoolean()) return e.evalBoolean(vn);
    public boolean evalBoolean(VTDNav vn) {        boolean a = false;        vn.push2();        // record teh stack size        int size = vn.contextStack2.size;        try {            a = (evalNodeSet(vn) != -1);        } catch (Exception e) {        }        //rewind stack        vn.contextStack2.size = size;        reset(vn);        vn.pop2();        return a;    }