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 badmatch(match, badfn):
    """Make a copy of the given matcher, replacing its bad method with the given
    one.
    """
    m = copy.copy(match)
    m.bad = badfn
    return m