FastAPI uses a **unique ID** for each *path operation*, it is used for the **operation ID** and also for the names of any needed custom models, for requests or responses.

You can customize that function. It takes an `APIRoute` and outputs a string.

For example, here it is using the first tag (you will probably have only one tag) and the *path operation* name (the function name).

## Motivation

Let's start with a simple example:

```Python
{!../../../docs_src/python_types/tutorial001.py!}
```

Calling this program outputs:

```
John Doe
```

The function does the following:

* Takes a `first_name` and `last_name`.
* Converts the first letter of each one to upper case with `title()`.

!!! danger
    Never store the plain password of a user or send it in a response like this, unless you know all the caveats and you know what you are doing.

## Add an output model

We can instead create an input model with the plaintext password and an output model without it:

=== "Python 3.10+"

    ```Python hl_lines="9  11  16"
    {!> ../../../docs_src/response_model/tutorial003_py310.py!}
    ```

<font color="#4E9A06">INFO</font>:     Waiting for application startup.
<font color="#4E9A06">INFO</font>:     Application startup complete.
```

</div>

In the output, there's a line with something like:

```hl_lines="4"
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

That line shows the URL where your app is being served, in your local machine.

Building docs for: en
Building docs for: es
Successfully built docs for: es
```

</div>

This builds all those independent MkDocs sites for each language, combines them, and generates the final output at `./site/`.

Then you can serve that with the command `serve`:

<div class="termy">

```console
// Use the command "serve" after running "build-all"
$ python ./scripts/docs.py serve

    * JSON.
    * Path parameters.
    * Query parameters.
    * Cookies.
    * Headers.
    * Form.
    * File.
* <abbr title="detta anche: serialization, parsing, marshalling">Conversione</abbr> dei dati di output: converte dati e tipi di Python a dati per la rete (come JSON):
    * Converte i tipi di Python (`str`, `int`, `float`, `bool`, `list`, ecc).
    * Oggetti `datetime`.
    * Oggetti `UUID`.
    * Modelli del database.

Ce "attendre quelque chose d'autre" fait généralement référence à des opérations <abbr title="Input/Output ou Entrées et Sorties ">I/O</abbr> qui sont relativement "lentes" (comparées à la vitesse du processeur et de la mémoire RAM) telles qu'attendre que :

* de la donnée soit envoyée par le client à travers le réseau

<div class="termy">

```console
$ openssl rand -hex 32

09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7
```

</div>

And copy the output to the variable `SECRET_KEY` (don't use the one in the example).

Create a variable `ALGORITHM` with the algorithm used to sign the JWT token and set it to `"HS256"`.

Create a variable for the expiration of the token.

(cerca de 100 nanosegundos), por favor observe que no **FastAPI** o efeito pode ser bem o oposto. Nesses casos, é melhor usar `async def` a menos que suas *funções de operação de rota* utilizem código que performem bloqueamento <abbr title="Input/Output: disco lendo ou escrevendo, comunicações de rede.">IO</abbr>.

Ainda, em ambas as situações, as chances são que o **FastAPI** será [ainda mais rápido](index.md#performance){.internal-link target=_blank} do que (ou ao menos comparável a)...

    * Path parameters.
    * Query parameters.
    * Cookies.
    * Headers.
    * Formularios.
    * Archivos.
* <abbr title="en inglés: serialization, parsing, marshalling">Conversión</abbr> de datos de output: convirtiendo de datos y tipos de Python a datos para la red (como JSON):
    * Convertir tipos de Python (`str`, `int`, `float`, `bool`, `list`, etc).
    * Objetos `datetime`.
    * Objetos `UUID`.