```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
```

=== "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

      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

    "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"]

    🗄 🔧 ⚫️ 🤙 <a href="https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#operation-object" class="external-link" target="_blank">🛠️ 🎚</a>.

⚫️ ✔️ 🌐 ℹ 🔃 *➡ 🛠️* &amp; ⚙️ 🏗 🏧 🧾.

⚫️ 🔌 `tags`, `parameters`, `requestBody`, `responses`, ♒️.

👉 *➡ 🛠️*-🎯 🗄 🔗 🛎 🏗 🔁 **FastAPI**, ✋️ 👆 💪 ↔ ⚫️.

!!! tip
    👉 🔅 🎚 ↔ ☝.

      const pathData = paths[pathKey]
      for (const method of Object.keys(pathData)) {
        const operation = pathData[method]
        if (operation.tags && operation.tags.length > 0) {
          const tag = operation.tags[0]
          const operationId = operation.operationId
          const toRemove = `${tag}-`
          if (operationId.startsWith(toRemove)) {

    ```

## Set-Typen

Aber dann denken wir darüber nach und stellen fest, dass sich die Tags nicht wiederholen sollen, es sollen eindeutige Strings sein.

Python hat einen Datentyp speziell für Mengen eindeutiger Dinge: das <abbr title="Menge">`set`</abbr>.

Deklarieren wir also `tags` als Set von Strings.

=== "Python 3.10+"

    ```Python hl_lines="12"

<img src="/img/tutorial/generate-clients/image05.png">

## FastAPI App with Tags

In many cases your FastAPI app will be bigger, and you will probably use tags to separate different groups of *path operations*.

For example, you could have a section for **items** and another section for **users**, and they could be separated by tags:

=== "Python 3.9+"

    ```Python hl_lines="21  26  34"

⏮️ 👉 📳, 🏧 🛠️ 🩺 🔜 👀 💖:

<img src="/img/tutorial/metadata/image01.png">

## 🗃 🔖

👆 💪 🚮 🌖 🗃 🎏 🔖 ⚙️ 👪 👆 ➡ 🛠️ ⏮️ 🔢 `openapi_tags`.

⚫️ ✊ 📇 ⚗ 1️⃣ 📖 🔠 🔖.

🔠 📖 💪 🔌:

* `name` (**✔**): `str` ⏮️ 🎏 📛 👆 ⚙️ `tags` 🔢 👆 *➡ 🛠️* &amp; `APIRouter`Ⓜ.
* `description`: `str` ⏮️ 📏 📛 🔖. ⚫️ 💪 ✔️ ✍ &amp; 🔜 🎦 🩺 🎚.
* `externalDocs`: `dict` 🔬 🔢 🧾 ⏮️:

    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/users/": {
                "get": {
                    "tags": ["users"],
                    "summary": "Read Users",
                    "operationId": "read_users_users__get",
                    "parameters": [
                        {