Poor introduction to dopamine

So I tried following the [overview](https://google.github.io/dopamine/docs/) and - to be honest - this has been a pain.

```
The entry point to the standard Atari 2600 experiment is [dopamine/discrete_domains/train.py](https://github.com/google/dopamine/blob/master/dopamine/discrete_domains/train.py). To run the basic DQN agent,

python -um dopamine.discrete_domains.train \
--base_dir /tmp/dopamine_runs \
--gin_files dopamine/agents/dqn/configs/dqn.gin
```
This raises loads of errors:
- First all the missing imports (I fixed those using `pipreqs`).
- Then ModuleNotFoundError: No module named 'dopamine.metrics' (described in GH-196) that I fixed by changing all `from dopamine.metrics` to `from metrics`.
- Finaly I've got Gym complaining it doesn't distribute ROMs anymore:
```
gym.error.Error: We're Unable to find the game "Pong". Note: Gym no longer distributes ROMs. If you own a license to use the necessary ROMs for research purposes you can download them via `pip install gym[accept-rom-license]`. Otherwise, you should try importing "Pong" via the command `ale-import-roms`. If you believe this is a mistake perhaps your copy of "Pong" is unsupported. To check if this is the case try providing the environment variable `PYTHONWARNINGS=default::ImportWarning:ale_py.roms`. For more information see: https://github.com/mgbellemare/Arcade-Learning-Environment#rom-management
```
I believe all of this should run onto the core and atari containers that I created following the readme but I don't see where this is explained...

So I started looking at the colabs hoping to find some more infos but I got loads of errors...

[agents.ipynb](https://colab.research.google.com/github/google/dopamine/blob/master/dopamine/colab/agents.ipynb) in `Load baseline data`
```
---------------------------------------------------------------------------

TypeError Traceback (most recent call last)

[](https://localhost:8080/#) in ()
1 # @title Load baseline data
2 get_ipython().system('gsutil -q -m cp -R gs://download-dopamine-rl/preprocessed-benchmarks/* /content/')
----> 3 experimental_data = colab_utils.load_baselines('/content')

1 frames

[/usr/lib/python3.7/copyreg.py](https://localhost:8080/#) in _reconstructor(cls, base, state)
41 def _reconstructor(cls, base, state):
42 if base is object:
---> 43 obj = object.__new__(cls)
44 else:
45 obj = base.__new__(cls, state)

TypeError: object.__new__(BlockManager) is not safe, use BlockManager.__new__()
```

[load_statistics.ipynb](https://colab.research.google.com/github/google/dopamine/blob/master/dopamine/colab/load_statistics.ipynb) in `Load the baseline data`
```
---------------------------------------------------------------------------

TypeError Traceback (most recent call last)

in ()
2
3 get_ipython().system('gsutil -q -m cp -R gs://download-dopamine-rl/preprocessed-benchmarks/* /content/')
----> 4 experimental_data = colab_utils.load_baselines('/content')

1 frames

/usr/lib/python3.7/copyreg.py in _reconstructor(cls, base, state)
41 def _reconstructor(cls, base, state):
42 if base is object:
---> 43 obj = object.__new__(cls)
44 else:
45 obj = base.__new__(cls, state)

TypeError: object.__new__(BlockManager) is not safe, use BlockManager.__new__()
```

[agent_visualizer.ipynb](https://colab.research.google.com/github/google/dopamine/blob/master/dopamine/colab/agent_visualizer.ipynb) in `Generate the video`
```
pygame 2.1.2 (SDL 2.0.16, Python 3.7.13)
Hello from the pygame community. https://www.pygame.org/contribute.html
WARNING:tensorflow:From /usr/local/lib/python3.7/dist-packages/tensorflow/python/compat/v2_compat.py:107: disable_resource_variables (from tensorflow.python.ops.variable_scope) is deprecated and will be removed in a future version.
Instructions for updating:
non-resource variables are not supported in the long term

---------------------------------------------------------------------------

Exception Traceback (most recent call last)

[](https://localhost:8080/#) in ()
4 example_viz_lib.run(agent='rainbow', game='SpaceInvaders', num_steps=num_steps,
5 root_dir='/tmp/agent_viz', restore_ckpt='/tmp/tf_ckpt-199',
----> 6 use_legacy_checkpoint=True)

15 frames

[/usr/local/lib/python3.7/dist-packages/atari_py/games.py](https://localhost:8080/#) in get_game_path(game_name)
18 path = os.path.join(_games_dir, game_name) + ".bin"
19 if not os.path.exists(path):
---> 20 raise Exception('ROM is missing for %s, see https://github.com/openai/atari-py#roms for instructions' % (game_name,))
21 return path
22

Exception: ROM is missing for space_invaders, see https://github.com/openai/atari-py#roms for instructions
In call to configurable 'create_atari_environment' ()
In call to configurable 'Runner' ()
```

[agent_visualizer.ipynb](https://colab.research.google.com/github/google/dopamine/blob/master/dopamine/colab/jax_agent_visualizer.ipynb) in `Generate video`
```
WARNING:tensorflow:From /usr/local/lib/python3.7/dist-packages/tensorflow/python/compat/v2_compat.py:107: disable_resource_variables (from tensorflow.python.ops.variable_scope) is deprecated and will be removed in a future version.
Instructions for updating:
non-resource variables are not supported in the long term

---------------------------------------------------------------------------

Exception Traceback (most recent call last)

[](https://localhost:8080/#) in ()
12 gin.parse_config(config)
13 runner = example_viz_lib.MyRunner(base_dir, '/tmp/ckpt.199',
---> 14 AGENT_CREATORS[agent])
15 runner.visualize(base_dir / 'images', num_global_steps=200)

13 frames

[/usr/local/lib/python3.7/dist-packages/atari_py/games.py](https://localhost:8080/#) in get_game_path(game_name)
18 path = os.path.join(_games_dir, game_name) + ".bin"
19 if not os.path.exists(path):
---> 20 raise Exception('ROM is missing for %s, see https://github.com/openai/atari-py#roms for instructions' % (game_name,))
21 return path
22

Exception: ROM is missing for breakout, see https://github.com/openai/atari-py#roms for instructions
In call to configurable 'create_atari_environment' ()
In call to configurable 'Runner' ()
```

happily [tensorboard.ipynb](https://colab.research.google.com/github/google/dopamine/blob/master/dopamine/colab/tensorboard.ipynb) functions properly and [cartpole.ipynb](https://colab.research.google.com/github/google/dopamine/blob/master/dopamine/colab/cartpole.ipynb) too.

Overall, all of this makes for a very poor introduction to dopamine.