<SYSTEM_TASK:>
Given the following text description, write Python code to implement the functionality described below step by step
<END_TASK>
<USER_TASK:>
Description:
 (document-tag-to-refer-to)=
Creating an Example
This is an example template file for writing Jupyter Notebooks in markdown, using MyST.
For more information on MyST notebooks, see the
MyST-NB documentation.
If you want to learn more about the MyST parser, see the
MyST documentation.
MyST is common markdown compliant, so if you can use plain markdown here.
In case you need to execute restructured text (rSt) directives, you can use {eval-rst} to execute the code.
For instance, a here's a note written in rSt
Step1:  Hiding and removing cells
You can hide cells, so that they will toggle when you click on the cell header.
You can use different 
Step2:  
<ASSISTANT_TASK:>
Python Code:
import ray
import ray.rllib.agents.ppo as ppo
from ray import serve
def train_ppo_model():
    trainer = ppo.PPOTrainer(
        config={"framework": "torch", "num_workers": 0},
        env="CartPole-v0",
    )
    # Train for one iteration
    trainer.train()
    trainer.save("/tmp/rllib_checkpoint")
    return "/tmp/rllib_checkpoint/checkpoint_000001/checkpoint-1"
checkpoint_path = train_ppo_model()
Explanation: (document-tag-to-refer-to)=
Creating an Example
This is an example template file for writing Jupyter Notebooks in markdown, using MyST.
For more information on MyST notebooks, see the
MyST-NB documentation.
If you want to learn more about the MyST parser, see the
MyST documentation.
MyST is common markdown compliant, so if you can use plain markdown here.
In case you need to execute restructured text (rSt) directives, you can use {eval-rst} to execute the code.
For instance, a here's a note written in rSt:
```{eval-rst}
.. note::
A note written in reStructuredText.
```
{margin}
You can create margins with this syntax for smaller notes that don't make it into the main
text.
You can also easily define footnotes.[^example]
[^example]: This is a footnote.
Adding code cells
End of explanation
# This can be useful if you don't want to clutter the page with details.
import ray
import ray.rllib.agents.ppo as ppo
from ray import serve
Explanation: Hiding and removing cells
You can hide cells, so that they will toggle when you click on the cell header.
You can use different :tags: like hide-cell, hide-input, or hide-output to hide cell content,
and you can use remove-cell, remove-input, or remove-output to remove the cell completely when rendered.
Those cells will still show up in the notebook itself, e.g. when you launch it in binder.
End of explanation
ray.shutdown()
Explanation: :::{tip}
Here's a quick tip.
:::
:::{note}
And this is a note.
:::
The following cell will be removed and not render:
End of explanation
<END_TASK>