def get_next_id(self):
        try:
            query = {'_id': 'last_id'}
            update = {'$inc': {'id': 1}}
            fn = self.db.internal.find_and_modify
            row = fn(query, update, upsert=True, new=True)
        except Exception as e:
            raise DatabaseException(e)
        return row['id']
def __init__(self, directory=None):
        if directory is None:
                directory = []
        import copy
        self.directory = copy.deepcopy(directory)
        self.bound = False
        self.start_tls_called = False
        self.extend = self.Extend(self)

        self.operation = {
                    "!" : self._search_not,
                    "&" : self._search_and,
                    "|" : self._search_or,
            }