```Traceback (most recent call last):


 "tutorial_agent.py", line 38, in <module>

world.parley()


 "/Users/user_name/ParlAI/parlai/core/worlds.py", line 249, in parley

acts[1] = agents[1].act()


 "tutorial_agent.py", line 25, in act

reply['text'] = random.choice(cands)


 "/Users/user_name/anaconda3/envs/virtualenv/lib/python3.6/random.py", line 261, in choice

return seq[i]
TypeError: 'set' object does not support indexing

Traceback (most recent call last):


 "tools/train.py", line 90, in <module>

main()


 "tools/train.py", line 86, in main

logger=logger)


 "/home/paperspace/miniconda3/envs/pytorch/lib/python3.7/site-packages/mmdet/apis/train.py", line 59, in train_detector

_non_dist_train(model, dataset, cfg, validate=validate)


 "/home/paperspace/miniconda3/envs/pytorch/lib/python3.7/site-packages/mmdet/apis/train.py", line 121, in _non_dist_train

runner.run(data_loaders, cfg.workflow, cfg.total_epochs)


 "/home/paperspace/miniconda3/envs/pytorch/lib/python3.7/site-packages/mmcv/runner/runner.py", line 355, in run

epoch_runner(data_loaders[i], **kwargs)


 "/home/paperspace/miniconda3/envs/pytorch/lib/python3.7/site-packages/mmcv/runner/runner.py", line 257, in train

for i, data_batch in enumerate(data_loader):


 "/home/paperspace/miniconda3/envs/pytorch/lib/python3.7/site-packages/torch/utils/data/dataloader.py", line 637, in __next__

return self._process_next_batch(batch)


 "/home/paperspace/miniconda3/envs/pytorch/lib/python3.7/site-packages/torch/utils/data/dataloader.py", line 658, in _process_next_batch

raise batch.exc_type(batch.exc_msg)
TypeError: Traceback (most recent call last):
