///

### 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 }

#### Check the `openapi.json` { #check-the-openapi-json }

If you are curious about how the raw OpenAPI schema looks like, FastAPI automatically generates a JSON (schema) with the descriptions of all your API.

Nevertheless, you still enforce those scopes, or any other security/authorization requirement, however you need, in your code.

In many cases, OAuth2 with scopes can be an overkill.

But if you know you need it, or you are curious, keep reading.

///

## OAuth2 scopes and OpenAPI { #oauth2-scopes-and-openapi }

The OAuth2 specification defines "scopes" as a list of strings separated by spaces.

/// warning

You can probably skip this.

These are very technical details of how **FastAPI** works underneath.

If you have quite some technical knowledge (coroutines, threads, blocking, etc.) and are curious about how FastAPI handles `async def` vs normal `def`, go ahead.

///

### Path operation functions { #path-operation-functions }

kunneppu.hokkaido.jp
kunohe.iwate.jp
kuokgroup
kurashiki.okayama.jp
kurate.fukuoka.jp
kure.hiroshima.jp
kurgan.su
kuriyama.hokkaido.jp
kurobe.toyama.jp
kurogi.fukuoka.jp
kuroishi.aomori.jp
kuroiso.tochigi.jp
kuromatsunai.hokkaido.jp
kuron.jp
kurotaki.nara.jp
kurume.fukuoka.jp
kusatsu.gunma.jp
kusatsu.shiga.jp
kushima.miyazaki.jp
kushimoto.wakayama.jp
kushiro.hokkaido.jp

kunneppu.hokkaido.jp
kunohe.iwate.jp
kuokgroup
kurashiki.okayama.jp
kurate.fukuoka.jp
kure.hiroshima.jp
kurgan.su
kuriyama.hokkaido.jp
kurobe.toyama.jp
kurogi.fukuoka.jp
kuroishi.aomori.jp
kuroiso.tochigi.jp
kuromatsunai.hokkaido.jp
kuron.jp
kurotaki.nara.jp
kurume.fukuoka.jp
kusatsu.gunma.jp
kusatsu.shiga.jp
kushima.miyazaki.jp
kushimoto.wakayama.jp
kushiro.hokkaido.jp

yaizu.shizuoka.jp
yoshida.shizuoka.jp
ashikaga.tochigi.jp
bato.tochigi.jp
haga.tochigi.jp
ichikai.tochigi.jp
iwafune.tochigi.jp
kaminokawa.tochigi.jp
kanuma.tochigi.jp
karasuyama.tochigi.jp
kuroiso.tochigi.jp
mashiko.tochigi.jp
mibu.tochigi.jp
moka.tochigi.jp
motegi.tochigi.jp
nasu.tochigi.jp
nasushiobara.tochigi.jp
nikko.tochigi.jp
nishikata.tochigi.jp
nogi.tochigi.jp

I would expect `typing_extensions.Doc` to be deprecated and then removed at some point from `typing_extensions`, for that reason there's the new `annotated-doc` micro-package. If you are curious about this, you can read more in the repo for [`annotated-doc`](https://github.com/fastapi/annotated-doc).

This new version `0.120.0` only contains that transition to the new home package for that utility class `Doc`.