## docstringを用いた説明

説明文は長くて複数行におよぶ傾向があるので、関数<abbr title="ドキュメントに使用される関数内の最初の式（変数に代入されていない）としての複数行の文字列">docstring</abbr>内に*path operation*の説明文を宣言できます。すると、**FastAPI** は説明文を読み込んでくれます。

docstringに<a href="https://en.wikipedia.org/wiki/Markdown" class="external-link" target="_blank">Markdown</a>を記述すれば、正しく解釈されて表示されます。（docstringのインデントを考慮して）

{* ../../docs_src/path_operation_configuration/tutorial004.py hl[19:27] *}

これは対話的ドキュメントで使用されます:

# WebSockets { #websockets }

You can use <a href="https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API" class="external-link" target="_blank">WebSockets</a> with **FastAPI**.

## Install `WebSockets` { #install-websockets }

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `websockets`:

<div class="termy">

```console
$ pip install websockets

---> 100%

                return "lang";
            }
        };
        ComponentUtil.setFessConfig(mockConfig);

        // Setup mock request manager
        RequestManager mockRequestManager = createMockRequestManager("en-GB");

        // Execute
        OptionalThing<Locale> result = provider.findBusinessLocale(null, mockRequestManager);

        // Verify
        assertTrue(result.isPresent());

✋️ 🕐❔ 📨 🔌 📁, ⚫️ 🗜 `multipart/form-data`. 🚥 👆 ⚙️ `File`, **FastAPI** 🔜 💭 ⚫️ ✔️ 🤚 📁 ⚪️➡️ ☑ 🍕 💪.

🚥 👆 💚 ✍ 🌖 🔃 👉 🔢 &amp; 📨 🏑, 👳 <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">🏇</abbr> 🕸 🩺 <code>POST</code></a>.

///

/// warning

* その後、`response` を返す前にさらに `response` を変更することもできます。

{* ../../docs_src/middleware/tutorial001.py hl[8:9,11,14] *}

/// tip | 豆知識

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">'X-'プレフィックスを使用</a>してカスタムの独自ヘッダーを追加できます。

            private static final long serialVersionUID = 1L;

            @Override
            public String getCrawlerDocumentHtmlDefaultLang() {
                return "en";
            }
        });
        assertEquals("en", systemHelper.normalizeHtmlLang("ja"));
    }

    public void test_normalizeLang() {
        String value = null;
        assertNull(systemHelper.normalizeLang(value));

🔨 👈 👽 🔢 👈 🚫 💰 ⚛ ⚖️ 🔢 👯‍♂️ 🌅 ⚠ 👆 🔜 💪 🏪 💲 🌐 🔢 ⚖️ 🎏 🎱.

↩️ 👈, ⚫️ 🔜 👍 ↩️ ⚙️ `lifespan` 🔬 🔛.

## 📡 ℹ

📡 ℹ 😟 🤓. 👶

🔘, 🔫 📡 🔧, 👉 🍕 <a href="https://asgi.readthedocs.io/en/latest/specs/lifespan.html" class="external-link" target="_blank">🔆 🛠️</a>, &amp; ⚫️ 🔬 🎉 🤙 `startup` &amp; `shutdown`.

## 🎧 🈸

/**
 * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
 * should override one or more methods to modify the behavior of the backing multiset as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSortedMultiset} forward
 * <b>indiscriminately</b> to the methods of the delegate. For example, overriding {@link

   cheaper w.r.t. memory and CPU.
- Root credentials can now be changed easily. Before, a two-step process was required to
   change the cluster root credentials since they were used to en/decrypt the IAM data.
   So, both - the old and new credentials - had to be present at the same time during a rotation
   and the old credentials had to be removed once the rotation completed. This process is now gone.

/**
 * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
 * should override one or more methods to modify the behavior of the backing multiset as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSortedMultiset} forward
 * <b>indiscriminately</b> to the methods of the delegate. For example, overriding {@link