void ExistsMatchExpression::debugString(StringBuilder& debug, int level) const {
    _debugAddSpace(debug, level);
    debug << path() << " exists";
    MatchExpression::TagData* td = getTag();
    if (NULL != td) {
        debug << " ";
        td->debugString(&debug);
    }
    debug << "\n";
}
void ExistsMatchExpression::debugString(StringBuilder& debug, int level) const {
    _debugAddSpace(debug, level);
    debug << path() << " exists";
    MatchExpression::TagData* td = getTag();
    if (NULL != td) {
        debug << " ";
        td->debugString(&debug);
    }
    debug << "\n";
}