def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def __init__(self, matchers):
        m1 = matchers[0]
        super(unionmatcher, self).__init__(m1._root, m1._cwd)
        self.traversedir = m1.traversedir
        self._matchers = matchers