```Python hl_lines="1  4"
{!../../../docs_src/python_types/tutorial009.py!}
```

Using `Optional[str]` instead of just `str` will let the editor help you detecting errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

$ python ./scripts/docs.py live

<span style="color: green;">[INFO]</span> Serving on http://127.0.0.1:8008
<span style="color: green;">[INFO]</span> Start watching changes
<span style="color: green;">[INFO]</span> Start detecting changes
```

</div>

Das stellt die Dokumentation unter `http://127.0.0.1:8008` bereit.

Auf diese Weise können Sie die Dokumentation/Quelldateien bearbeiten und die Änderungen live sehen.

$ python ./scripts/docs.py live

<span style="color: green;">[INFO]</span> Serving on http://127.0.0.1:8008
<span style="color: green;">[INFO]</span> Start watching changes
<span style="color: green;">[INFO]</span> Start detecting changes
```

</div>

文档服务将运行在 `http://127.0.0.1:8008`。

这样，你可以编辑文档 / 源文件并实时查看更改。

!!! tip
    或者你也可以手动执行和该脚本一样的操作

    进入语言目录，如果是英文文档，目录则是 `docs/en/`:

    ```console

---

<div style="text-align: left; direction: ltr;">"If you're looking to learn one <strong>modern framework</strong> for building REST APIs, check out <strong>FastAPI</strong> [...] It's fast, easy to use and easy to learn [...]"</div>

```Python hl_lines="1"
{!../../../docs_src/python_types/tutorial003.py!}
```

Comme l'éditeur connaît le type des variables, vous n'avez pas seulement l'auto-complétion, mais aussi de la détection d'erreurs :

<img src="/img/python-types/image04.png">

Maintenant que vous avez connaissance du problème, convertissez `age` en <abbr title="string">chaîne de caractères</abbr> grâce à `str(age)` :