client to send the form field `grant_type` with the value `"password"`, which
    is required in the OAuth2 specification (it seems that for no particular reason),
    while for `OAuth2PasswordRequestForm` `grant_type` is optional.

    Read more about it in the

## Running on Startup

In most cases, when you create a web API, you want it to be **always running**, uninterrupted, so that your clients can always access it. This is of course, unless you have a specific reason why you want it to run only in certain situations, but most of the time you want it constantly running and **available**.

### In a Remote Server

                """
            ),
        ],
        reason: Annotated[
            Union[str, None],
            Doc(
                """
                The reason to close the WebSocket connection.

                It is UTF-8-encoded data. The interpretation of the reason is up to the
                application, it is not specified by the WebSocket specification.

### Классы как типы

Вы также можете объявить класс как тип переменной.

Допустим, у вас есть класс `Person` с полем `name`:

```Python hl_lines="1-3"
{!../../../docs_src/python_types/tutorial010.py!}
```

Тогда вы можете объявить переменную типа `Person`:

```Python hl_lines="6"
{!../../../docs_src/python_types/tutorial010.py!}
```

### Класи як типи

Ви також можете оголосити клас як тип змінної.

Скажімо, у вас є клас `Person` з імʼям:

```Python hl_lines="1-3"
{!../../../docs_src/python_types/tutorial010.py!}
```

Потім ви можете оголосити змінну типу `Person`:

```Python hl_lines="6"
{!../../../docs_src/python_types/tutorial010.py!}
```

<img src="/img/python-types/image06.png">

Notice that this means "`one_person` is an **instance** of the class `Person`".

It doesn't mean "`one_person` is the **class** called `Person`".

## Pydantic models

<a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> is a Python library to perform data validation.

You declare the "shape" of the data as classes with attributes.

| `license_info`...

Most of these settings are variable (can change), like database URLs. And many could be sensitive, like secrets.

For this reason it's common to provide them in environment variables that are read by the application.

## Environment Variables

!!! tip

!!! info
    In diesem Beispiel verwenden wir zwei erfundene benutzerdefinierte Header `X-Key` und `X-Token`.

    Aber in realen Fällen würden Sie bei der Implementierung von Sicherheit mehr Vorteile durch die Verwendung der integrierten [Sicherheits-Werkzeuge (siehe nächstes Kapitel)](../security/index.md){.internal-link target=_blank} erzielen.

---

Here's how to help others with questions (in discussions or issues):

### Understand the question

* Check if you can understand what is the **purpose** and use case of the person asking.

* Then check if the question (the vast majority are questions) is **clear**.