Now that we have all the security flow, let's make the application actually secure, using <abbr title="JSON Web Tokens">JWT</abbr> tokens and secure password hashing.

This code is something you can actually use in your application, save the password hashes in your database, etc.

We are going to start from where we left in the previous chapter and increment it.

## About JWT

JWT means "JSON Web Tokens".

///

```Python hl_lines="2  5-8  11"
{!> ../../docs_src/settings/tutorial001_pv1.py!}
```

////

/// tip

If you want something quick to copy and paste, don't use this example, use the last one below.

///

 *   <li><b>Convenience methods:</b> These are implementations of common operations that are
 *       typically implemented by opening a reader using one of the methods in the first category,
 *       doing something and finally closing the reader that was opened.
 * </ul>
 *
 * <p>Several methods in this class, such as {@link #readLines()}, break the contents of the source

```
`@app.get("/")`は直下の関数が下記のリクエストの処理を担当することを**FastAPI**に伝えます:

* パス `/`
* <abbr title="an HTTP GET method"><code>get</code> オペレーション</abbr>

/// info | "`@decorator` について"

Pythonにおける`@something`シンタックスはデコレータと呼ばれます。

「デコレータ」は関数の上に置きます。かわいらしい装飾的な帽子のようです（この用語の由来はそこにあると思います）。

「デコレータ」は直下の関数を受け取り、それを使って何かを行います。

私たちの場合、このデコレーターは直下の関数が**オペレーション** `get`を使用した**パス**` / `に対応することを**FastAPI** に通知します。

이로인해, FastAPI 0.99.0 이전 버전은 아직 OpenAPI 3.1.0 보다 낮은 버전을 사용했습니다.

///

### Pydantic과 FastAPI `examples`

`examples`를 Pydantic 모델 속에 추가할 때, `schema_extra` 혹은 `Field(examples=["something"])`를 사용하면 Pydantic 모델의 **JSON 스키마**에 해당 예시가 추가됩니다.

그리고 Pydantic 모델의 **JSON 스키마**는 API의 **OpenAPI**에 포함되고, 그 후 문서 UI 속에서 사용됩니다.

   */
  protected final class MultiExceptionListIterator implements ListIterator<E> {
    // TODO: track seen elements when order isn't guaranteed
    // TODO: verify contents afterward
    // TODO: something shiny and new instead of Stack
    // TODO: test whether null is supported (create a Feature)
    /**
     * The elements to be returned by future calls to {@code next()}, with the first at the top of
     * the stack.

 *
 * <h3>Comparison to alternatives</h3>
 *
 * <p><b>Note:</b> In some cases the differences explained below can be subtle. When it's unclear
 * which approach to use, <b>don't worry</b> too much about it; just pick something that seems
 * reasonable and it will be fine.
 *
 * <ul>
 *   <li>If checking whether the <i>caller</i> has violated your method or constructor's contract

These particular phases in a plugin’s lifecycle can probably be generalized to all plugins so could be something implemented in all plugins. Here we could have the descriptor either point to methods for each of these phases to execute or we could create a lifecycle in Plexus for these phases.

By validating the data with Pydantic we can make sure that we have, for example, exactly a `list` of `str` with the scopes and a `str` with the `username`.

Instead of, for example, a `dict`, or something else, as it could break the application at some point later, making it a security risk.

We also verify that we have a user with that username, and if not, we raise that same exception we created before.

            To properly test this, you need to remove existing toolchains:
            rm -rf ~/.m2/jdks/ ~/.m2/toolchains.xml
            (But don't run that if you have put something into ~/.m2/toolchains.xml yourself.)
            -->
            <execution>
              <id>download-11</id>
              <goals>
                <goal>toolchain</goal>
              </goals>