return buf.toString();
if (conds.isEmpty()) { return Code.TRUE; } else { return Code.join(conds, " and "); }
    String emit(Generator gen) {        QFrame query = gen.getFrame(m_operand);        if (!query.isSelect()) {            List values = query.getValues();            StringBuffer buf = new StringBuffer();            for (Iterator it = values.iterator(); it.hasNext(); ) {                QValue value = (QValue) it.next();                buf.append(value);                buf.append(" is not null");                if (it.hasNext()) {                    buf.append(" and ");                }            }            return buf.toString();        } else {            return "exists (" + m_operand.emit(gen) + ")";        }    }