```Python
say_hi(name=None)  # Dit werkt, None is geldig 🎉
```

Het goede nieuws is dat als je eenmaal Python 3.10 gebruikt, je je daar geen zorgen meer over hoeft te maken, omdat je dan gewoon `|` kunt gebruiken om unions van types te definiëren:

{* ../../docs_src/python_types/tutorial009c_py310.py hl[1,4] *}


Dan hoef je je geen zorgen te maken over namen als `Optional` en `Union`. 😎

#### Generieke typen

  avatarUrl: https://avatars.githubusercontent.com/u/109919500?u=b9b13d598dddfab529a52d264df80a900bfe7060&v=4
  url: https://github.com/YuriiMotov
- login: github-actions
  count: 769
  avatarUrl: https://avatars.githubusercontent.com/in/15368?v=4
  url: https://github.com/apps/github-actions
- login: Kludex
  count: 654
  avatarUrl: https://avatars.githubusercontent.com/u/7353520?u=df8a3f06ba8f55ae1967a3e2d5ed882903a4e330&v=4

///

### Understand that Code { #understand-that-code }

The important point is just using **`AfterValidator` with a function inside `Annotated`**. Feel free to skip this part. 🤸

---

But if you're curious about this specific code example and you're still entertained, here are some extra details.

#### String with `value.startswith()` { #string-with-value-startswith }

* `internal`: Internal
    * Use this for changes that only affect how the repo is managed. For example upgrades to internal dependencies, changes in GitHub Actions or scripts, etc.

/// tip

</p>
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**FastAPI** n'impose pas de sens spécifique à chacune d'elle.

Les informations qui sont présentées ici forment une directive générale, pas des obligations.

Par exemple, quand l'on utilise **GraphQL**, toutes les actions sont effectuées en utilisant uniquement des opérations `POST`.

///

### Étape 4 : définir la **fonction de chemin**.

Voici notre "**fonction de chemin**" (ou fonction d'opération de chemin) :

/// note | 참고

<a href="https://docs.pydantic.dev/latest/concepts/types/#unions" class="external-link" target="_blank">`Union`</a>을 정의할때는 더 구체적인 타입을 먼저 포함하고, 덜 구체적인 타입을 그 뒤에 나열해야합니다. 아래 예제에서는 `Union[PlaneItem, CarItem]` 를 보면, 더 구체적인 `PlaneItem`이 `CarItem`보다 앞에 위치합니다.

///

</p>
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    FastAPI 프레임워크, 고성능, 간편한 학습, 빠른 코드 작성, 준비된 프로덕션
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</p>
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    FastAPI 🛠️, ↕ 🎭, ⏩ 💡, ⏩ 📟, 🔜 🏭
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