All the **logic** about how to register the URLs for webhooks and the code to actually send those requests is up to you. You write it however you want to in **your own code**.

## Documenting webhooks with **FastAPI** and OpenAPI

    ```

=== "Python 3.8+"

    ```Python hl_lines="81-83"
    {!> ../../../docs_src/websockets/tutorial003.py!}
    ```

To try it out:

* Open the app with several browser tabs.
* Write messages from them.
* Then close one of the tabs.

That will raise the `WebSocketDisconnect` exception, and all the other clients will receive a message like:

```
Client #1596980209979 left the chat
```

## Write the callback documentation code

This code won't be executed in your app, we only need it to *document* how that *external API* should look like.

If you need a 2 minute refresher of how to use Python types (even if you don't use FastAPI), check the short tutorial: [Python Types](python-types.md){.internal-link target=_blank}.

You write standard Python with types:

```Python
from datetime import date

from pydantic import BaseModel

# Declare a variable as a str
# and get editor support inside the function
def main(user_id: str):

| `minio_system_drive_writes_per_sec`            | `gauge`   | Writes per second on a drive                                       | `drive,set_index,drive_index,pool_index,server`     |
| `minio_system_drive_writes_kb_per_sec`         | `gauge`   | Kilobytes written per second on a drive                            | `drive,set_index,drive_index,pool_index,server`     |

### What is a Program

The word **program** is commonly used to describe many things:

* The **code** that you write, the **Python files**.
* The **file** that can be **executed** by the operating system, for example: `python`, `python.exe` or `uvicorn`.

Provides build logic, libraries, test suites and infrastructure to support developing and releasing Gradle.

### Documentation

Provides cross-cutting Gradle documentation and samples, along with the infrastructure to write, test, publish and host the documentation.

## Structure

Each platform and module has its own source directory under [platforms/](../platforms).

## Recap

* Import `FastAPI`.
* Create an `app` instance.
* Write a **path operation decorator** (like `@app.get("/")`).
* Write a **path operation function** (like `def root(): ...` above).

### Creating commits and writing commit messages

The commit messages that accompany your code changes are an important piece of documentation. Please follow these guidelines when creating commits:

* [Write good commit messages.](https://cbea.ms/git-commit/#seven-rules)

### Internal

* ✏️ Update Pydantic links to dotenv support. PR [#10511](https://github.com/tiangolo/fastapi/pull/10511) by [@White-Mask](https://github.com/White-Mask).
* ✏️ Update links in `docs/en/docs/async.md` and `docs/zh/docs/async.md` to make them relative. PR [#10498](https://github.com/tiangolo/fastapi/pull/10498) by [@hasnatsajid](https://github.com/hasnatsajid).