=== "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
```

!!! tip

Then open 10 tabs at <a href="http://127.0.0.1:8000/docs#/default/read_slow_users_slowusers__get" class="external-link" target="_blank">http://127.0.0.1:8000/docs#/default/read_slow_users_slowusers__get</a> at the same time.

Go to the *path operation* "Get `/slowusers/`" in all of the tabs. Use the "Try it out" button and execute the request in each tab, one right after the other.

      name: Switch to light mode
  features:
  - search.suggest
  - search.highlight
  - content.tabs.link
  - navigation.indexes
  - content.tooltips
  - navigation.path
  - content.code.annotate
  - content.code.copy
  - content.code.select
  - navigation.tabs
  icon:
    repo: fontawesome/brands/github-alt
  logo: img/icon-white.svg
  favicon: img/favicon.png
  language: en

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

Zum Ausprobieren:

* Öffnen Sie die Anwendung mit mehreren Browser-Tabs.
* Schreiben Sie Nachrichten in den Tabs.
* Schließen Sie dann einen der Tabs.

Das wird die Ausnahme `WebSocketDisconnect` auslösen und alle anderen Clients erhalten eine Nachricht wie:

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

    "UP",  # pyupgrade
]
ignore = [
    "E501",  # line too long, handled by black
    "B008",  # do not perform function calls in argument defaults
    "C901",  # too complex
    "W191",  # indentation contains tabs
]

[tool.ruff.lint.per-file-ignores]
"__init__.py" = ["F401"]
"docs_src/dependencies/tutorial007.py" = ["F821"]
"docs_src/dependencies/tutorial008.py" = ["F821"]
"docs_src/dependencies/tutorial009.py" = ["F821"]

        ] = "/openapi.json",
        openapi_tags: Annotated[
            Optional[List[Dict[str, Any]]],
            Doc(
                """
                A list of tags used by OpenAPI, these are the same `tags` you can set
                in the *path operations*, like:

                * `@app.get("/users/", tags=["users"])`
                * `@app.get("/items/", tags=["items"])`

@app.get("/users/", tags=["users"])
async def get_users():
    return [{"name": "Harry"}, {"name": "Ron"}]


@app.get("/items/", tags=["items"])
async def get_items():

    price: float
    tax: float | None = None
    tags: set[str] = set()


@app.post("/items/", response_model=Item, tags=["items"])
async def create_item(item: Item):
    return item


@app.get("/items/", tags=["items"])
async def read_items():
    return [{"name": "Foo", "price": 42}]


@app.get("/users/", tags=["users"])
async def read_users():

    return f"{route.tags[0]}-{route.name}"


app = FastAPI(generate_unique_id_function=custom_generate_unique_id)


class Item(BaseModel):
    name: str
    price: float


class ResponseMessage(BaseModel):
    message: str


class User(BaseModel):
    username: str
    email: str


@app.post("/items/", response_model=ResponseMessage, tags=["items"])

                        "tax": {
                            "title": "Tax",
                            "anyOf": [{"type": "number"}, {"type": "null"}],
                        },
                        "tags": {
                            "title": "Tags",
                            "uniqueItems": True,
                            "type": "array",
                            "items": {"type": "string"},
                            "default": [],