예를 들어 다음과 같은 `main.py` 파일이 있다고 합시다:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | 팁

<a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 의 두 번째 인자는 반환할 기본값입니다.

여기서는 `"World"`를 넣었기에 기본값으로써 사용됩니다. 넣지 않으면 `None` 이 기본값으로 사용됩니다.

///

## Version 4.0.0-RC1

_2019-06-03_

 *  First stable preview of OkHttp 4.


## Version 3.x

[Change log](https://square.github.io/okhttp/changelog_3x/)


 [bom]: https://docs.gradle.org/6.2/userguide/platforms.html#sub:bom_import
 [bouncy_castle_releases]: https://www.bouncycastle.org/releasenotes.html
 [CVE-2021-0341]: https://nvd.nist.gov/vuln/detail/CVE-2021-0341

# Default options should come above this line.

# Android configs. Bazel needs to have --cpu and --fat_apk_cpu both set to the
# target CPU to build transient dependencies correctly. See
# https://docs.bazel.build/versions/master/user-manual.html#flag--fat_apk_cpu
build:android --config=clang_local
build:android --crosstool_top=//external:android/crosstool
build:android --host_crosstool_top=@bazel_tools//tools/cpp:toolchain

覚えておくべき重要なことは、`sub`キーはアプリケーション全体で一意の識別子を持ち、文字列である必要があるということです。

## 確認

サーバーを実行し、ドキュメントに移動します：<a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>

次のようなユーザーインターフェイスが表示されます：

<img src="/img/tutorial/security/image07.png">

前回と同じ方法でアプリケーションの認可を行います。

次の認証情報を使用します：

Username: `johndoe`

                          example: "Open Source Enterprise Search Server: Fess — Fe..."
                        digest:
                          type: string
                          example: "Docs » Open Source Enterprise Search Server: Fess Commercial Support Open Source Enterprise Search Server: Fess What is Fess ? Fess is very powerful and easily deployable Enterprise Search Server. ..."
                        host:

* **Session and Cookie** desteği.
* 100% test kapsayıcılığı.
* 100% typeları belirtilmiş codebase.

## Pydantic özellikleri

**FastAPI** ile <a href="https://docs.pydantic.dev/" class="external-link" target="_blank"><strong>Pydantic</strong></a> tamamiyle uyumlu ve üzerine kurulu. Yani FastAPI üzerine ekleme yapacağınız herhangi bir Pydantic kodu da çalışacaktır.

* Obsługa **sesji i ciasteczek**.
* 100% pokrycie testami.
* 100% adnotacji typów.

## Cechy Pydantic

**FastAPI** jest w pełni kompatybilny z (oraz bazuje na) <a href="https://docs.pydantic.dev/" class="external-link" target="_blank"><strong>Pydantic</strong></a>. Tak więc każdy dodatkowy kod Pydantic, który posiadasz, również będzie działał.

* **Sitzungs- und Cookie**-Unterstützung.
* 100 % Testabdeckung.
* 100 % Typen annotierte Codebasis.

## Pydantic's Merkmale

**FastAPI** ist vollkommen kompatibel (und basiert auf) <a href="https://docs.pydantic.dev/" class="external-link" target="_blank"><strong>Pydantic</strong></a>. Das bedeutet, wenn Sie eigenen Pydantic Quellcode haben, funktioniert der.

/// warning

These are technical details that you might skip if it's not important for you now.

///

`RequestValidationError` is a sub-class of Pydantic's <a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>.

* Cobertura de tests del 100%.
* Código completamente anotado con tipos.

## Funcionalidades de Pydantic

**FastAPI** es totalmente compatible con (y está basado en) <a href="https://docs.pydantic.dev/" class="external-link" target="_blank"><strong>Pydantic</strong></a>. Por lo tanto, cualquier código adicional de Pydantic que tengas, también funcionará.