* read operations will work correctly. To allow concurrent update operations, wrap your multimap
 * with a call to {@link Multimaps#synchronizedSetMultimap}.
 *
 * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code LinkedHashMultimap}
 * in a way that affects its {@link Object#equals} behavior. Undefined behavior and bugs will
 * result.
 *

當 `with` 區塊結束時，它會確保關閉檔案，即使發生了例外也一樣。

當你建立一個含 `yield` 的相依時，**FastAPI** 會在內部為它建立一個情境管理器，並與其他相關工具結合。

### 在含 `yield` 的相依中使用情境管理器 { #using-context-managers-in-dependencies-with-yield }

/// warning

這大致算是一個「進階」概念。

如果你剛開始學習 **FastAPI**，此處可以先跳過。

///

在 Python 中，你可以透過[建立一個擁有 `__enter__()` 與 `__exit__()` 兩個方法的類別](https://docs.python.org/3/reference/datamodel.html#context-managers)來建立情境管理器。

 * {@code SetMultimap} instead, two presidents would have vanished, and last names might or might
 * not appear in chronological order.
 *
 * <p><b>Warning:</b> instances of type {@code Multimap} may not implement {@link Object#equals} in
 * the way you expect. Multimaps containing the same key-value pairs, even in the same order, may or

ここまでを理解できていれば、そうしたセキュリティ用ユーティリティが内部でどのように動いているかも理解できています。

///

## `yield`、`HTTPException`、`except` とバックグラウンドタスクを伴う依存関係 { #dependencies-with-yield-httpexception-except-and-background-tasks }

/// warning | 注意

これらの技術的詳細は、ほとんどの場合は不要です。

主に、0.121.0 より前の FastAPI アプリケーションがあり、`yield` を使う依存関係で問題が発生している場合に有用です。

///

`yield` を使う依存関係は、さまざまなユースケースに対応し、いくつかの問題を修正するために時間とともに進化してきました。ここでは変更点の概要を説明します。

每次你「使用」Facebook、Google、GitHub、Microsoft、X（Twitter）「登入」時，那個應用就是在使用帶有 scopes 的 OAuth2。

在本節中，你將看到如何在你的 FastAPI 應用中，用同樣的帶有 scopes 的 OAuth2 管理驗證與授權。

/// warning

這一節算是進階內容。如果你剛開始，可以先跳過。

你不一定需要 OAuth2 scopes，你可以用任何你想要的方式處理驗證與授權。

但帶有 scopes 的 OAuth2 可以很漂亮地整合進你的 API（透過 OpenAPI）與 API 文件。

無論如何，你仍然會在程式碼中，依你的需求，強制檢查那些 scopes，或其他任何安全性／授權需求。

 *
 * <p>If neither {@link #skipNulls()} nor {@link #useForNull(String)} is specified, the joining
 * methods will throw {@link NullPointerException} if any given element is null.
 *
 * <p><b>Warning: joiner instances are always immutable</b>; a configuration method such as {@code
 * useForNull} has no effect on the instance it is invoked on! You must store and use the new joiner

  /**
   * Returns a new target iterator each time it's called. This is the iterator you are trying to
   * test. This must return an Iterator that returns the expected elements passed to the constructor
   * in the given order. Warning: it is not enough to simply pull multiple iterators from the same
   * source Iterable, unless that Iterator is unmodifiable.
   */
  protected abstract I newTargetIterator();

  /**

 *       {@link #verifyNotNull(Object)} and {@link Preconditions#checkNotNull(Object)} perform the
 *       same function with more clarity.
 * </ul>
 *
 * <h3>Warning about performance</h3>
 *
 * <p>Remember that parameter values for message construction must all be computed eagerly, and
 * autoboxing and varargs array creation may happen as well, even when the verification succeeds and

<img src="/img/tutorial/behind-a-proxy/image02.png">

원하던 그대로입니다. ✔️

이는 FastAPI가 이 `root_path`를 사용해, OpenAPI에서 기본 `server`를 `root_path`가 제공한 URL로 생성하기 때문입니다.

## 추가 서버 { #additional-servers }

/// warning | 경고

이는 더 고급 사용 사례입니다. 건너뛰어도 괜찮습니다.

///

기본적으로 **FastAPI**는 OpenAPI 스키마에서 `root_path`의 URL로 `server`를 생성합니다.

하지만 예를 들어 동일한 docs UI가 스테이징과 프로덕션 환경 모두와 상호작용하도록 하려면, 다른 대안 `servers`를 제공할 수도 있습니다.

   * null, null, null]} regardless of the true comparison order of those three values (which might
   * not even implement {@link Comparable} at all).
   *
   * <p><b>Warning:</b> by definition, this comparator is not <i>consistent with equals</i> (as
   * defined {@linkplain Comparator here}). Avoid its use in APIs, such as {@link
   * TreeSet#TreeSet(Comparator)}, where such consistency is expected.