How to use the bsddb3.rnopen function in bsddb3

def get_filenames():
            result = []
            for filename in os.listdir(dirname):
                if filename.startswith(db_filename) and filename != db_filename:
                    file_time = int(filename.split("-")[-1])
                    if file_time > timestamp:
                        result.append(filename)
            result = sorted(result)
            if os.path.isfile(self.db_file):
                result += [db_filename]
            return result

        with self.lock:
            self.restoring_mode = True
            for filename in get_filenames():
                f = bsddb3.rnopen(os.path.join(dirname, filename), "r")
                for k, v in f.items():
                    try:
                        obj = cPickle.loads(v)
                        obj.Redo(self)
                    except Exception, e:
                        logging.exception("occurred in TagLogger while restoring from a journal : %s", e)
                f.close()
            self.restoring_mode = False

def Open(self, filename):
        self.file = bsddb3.rnopen(filename, "c")
        self.file_opened = True