// ```
//
// No matter which of the three exponent forms is used, no quantity may represent
// a number greater than 2^63-1 in magnitude, nor may it have more than 3 decimal
// places. Numbers larger or more precise will be capped or rounded up.
// (E.g.: 0.1m will rounded up to 1m.)
// This may be extended in the future if we require larger or smaller quantities.
//

It can't handle nested models very well. So, if the JSON body in the request is a JSON object that has inner fields that in turn are nested JSON objects, it cannot be properly documented and validated.

### We Make Mistakes

We, as humans, make **mistakes**, all the time. Software almost *always* has **bugs** hidden in different places. 🐛

And we as developers keep improving the code as we find those bugs and as we implement new features (possibly adding new bugs too 😅).

### Small Errors Automatically Handled

<a href="https://github.com/containous/traefik/releases" class="external-link" target="_blank">Laden Sie Traefik herunter</a>, es ist eine einzelne Binärdatei, Sie können die komprimierte Datei extrahieren und sie direkt vom Terminal aus ausführen.

Dann erstellen Sie eine Datei `traefik.toml` mit:

```TOML hl_lines="3"

We are going to include this `APIRouter` in the main `FastAPI` app, but first, let's check the dependencies and another `APIRouter`.

## Dependencies

We see that we are going to need some dependencies used in several places of the application.

So we put them in their own `dependencies` module (`app/dependencies.py`).

We will now use a simple dependency to read a custom `X-Token` header:

=== "Python 3.9+"

### Resumen

En resumen, declaras los tipos de parámetros, body, etc. **una vez** como parámetros de la función.

Lo haces con tipos modernos estándar de Python.

No tienes que aprender una sintaxis nueva, los métodos o clases de una library específica, etc.

Solo **Python** estándar.

Por ejemplo, para un `int`:

```Python
item_id: int
```

o para un modelo más complejo de `Item`:

```Python
item: Item

* La variable `prices` es un `dict`:
    * Los keys de este `dict` son de tipo `str` (Digamos que son el nombre de cada ítem).
    * Los valores de este `dict` son de tipo `float` (Digamos que son el precio de cada ítem).

### Clases como tipos

También puedes declarar una clase como el tipo de una variable.

Digamos que tienes una clase `Person`con un nombre:

```Python hl_lines="1-3"
{!../../../docs_src/python_types/tutorial009.py!}

    * `alias_priority`
    * `validation_alias`
    * `serialization_alias`
    * `discriminator`
    * `strict`
    * `multiple_of`
    * `allow_inf_nan`
    * `max_digits`
    * `decimal_places`
    * `json_schema_extra`

...you can read about them in the Pydantic docs.

* The parameter `regex` has been deprecated and replaced by `pattern`.

## Combining information

You can also combine response information from multiple places, including the `response_model`, `status_code`, and `responses` parameters.

          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,