new_games is a list of .tfrecord.zz new game records.

def update(self, new_games):
        """ new_games is a list of .tfrecord.zz new game records. """
        new_games.sort(key=os.path.basename)
        first_new_game = None
        for idx, game in enumerate(new_games):
            timestamp = file_timestamp(game)
            if timestamp <= self.examples[-1][0]:
                continue
            elif first_new_game is None:
                first_new_game = idx
                num_new_games = len(new_games) - idx
                print("Found {}/{} new games".format(
                    num_new_games, len(new_games)))
                self.total_updates += num_new_games
            self.examples.extend(self.func(game))
        if first_new_game is None:
            print("No new games", file_timestamp(
                new_games[-1]), self.examples[-1][0])