docs: def iget_batches(task_ids, batch_size=10):
      """Yield out a map of the keys and futures in batches of the batch size
      passed in.
      """
  
      make_key = lambda _id: ndb.Key(FuriousAsyncMarker, _id)
      for keys in i_batch(imap(make_key, task_ids), batch_size):
          yield izip(keys, ndb.get_multi_async(keys))