But in many cases, you will want to run several worker processes at the same time.

### Multiple Processes - Workers

The client (browser) will know that the response comes from the correct server because it is using the cryptography they agreed using the **HTTPS certificate** before.

### Multiple Applications

In the same server (or servers), there could be **multiple applications**, for example, other API programs or a database.

> Você tem que limpar uma grande casa suja.

*Sim, essa é toda a história*.

---

Não há espera em lugar algum, apenas um monte de trabalho para ser feito, em múltiplos cômodos da casa.

Você poderia ter chamadas como no exemplo dos hambúrgueres, primeiro a sala de estar, então a cozinha, mas você não está esperando por nada, apenas limpar e limpar, as chamadas não afetariam em nada.

By creating a function that is only dedicated to getting your user from a `username` (or any other parameter) independent of your *path operation function*, you can more easily re-use it in multiple parts and also add <abbr title="Automated test, written in code, that checks if another piece of code is working correctly.">unit tests</abbr> for it:

```Python hl_lines="36-42"

The files and form fields will be uploaded as form data and you will receive the files and form fields.

And you can declare some of the files as `bytes` and some as `UploadFile`.

!!! warning
    You can declare multiple `File` and `Form` parameters in a *path operation*, but you can't also declare `Body` fields that you expect to receive as JSON, as the request will have the body encoded using `multipart/form-data` instead of `application/json`.

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient


@pytest.fixture(name="client")
def get_client():
    from docs_src.body_multiple_params.tutorial001_an import app

    client = TestClient(app)
    return client


def test_post_body_q_bar_content(client: TestClient):
    response = client.put("/items/5?q=bar", json={"name": "Foo", "price": 50.5})
    assert response.status_code == 200

<img src="/img/tutorial/bigger-applications/image01.png">

## Include the same router multiple times with different `prefix`

You can also use `.include_router()` multiple times with the *same* router using different prefixes.

This could be useful, for example, to expose the same API under different prefixes, e.g. `/api/v1` and `/api/latest`.

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient


@pytest.fixture(name="client")
def get_client():
    from docs_src.body_multiple_params.tutorial003 import app

    client = TestClient(app)
    return client


def test_post_body_valid(client: TestClient):
    response = client.put(
        "/items/5",
        json={
            "importance": 2,

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient


@pytest.fixture(name="client")
def get_client():
    from docs_src.body_multiple_params.tutorial003_an import app

    client = TestClient(app)
    return client


def test_post_body_valid(client: TestClient):
    response = client.put(
        "/items/5",
        json={
            "importance": 2,

import pytest
from dirty_equals import IsDict
from fastapi.testclient import TestClient

from ...utils import needs_py310


@pytest.fixture(name="client")
def get_client():
    from docs_src.body_multiple_params.tutorial003_py310 import app

    client = TestClient(app)
    return client


@needs_py310
def test_post_body_valid(client: TestClient):
    response = client.put(
        "/items/5",
        json={