docs: 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])