{* ../../docs_src/advanced_middleware/tutorial002_py39.py hl[2,6:8] *}

Se soportan los siguientes argumentos:

* `allowed_hosts` - Una list de nombres de dominio que deberían ser permitidos como nombres de host. Se soportan dominios comodín como `*.example.com` para hacer coincidir subdominios. Para permitir cualquier nombre de host, usa `allowed_hosts=["*"]` u omite el middleware.

Dans cet exemple, la fonction de tâche écrira dans un fichier (afin de simuler un envoi d'email).

L'opération d'écriture n'utilisant ni `async` ni `await`, on définit la fonction avec un `def` normal.

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Ajouter une tâche d'arrière-plan

* **TCP no sabe acerca de "dominios"**. Solo sobre direcciones IP.
    * La información sobre el **dominio específico** solicitado va en los **datos HTTP**.
* Los **certificados HTTPS** "certifican" un **cierto dominio**, pero el protocolo y la encriptación ocurren a nivel de TCP, **antes de saber** con cuál dominio se está tratando.
* **Por defecto**, eso significaría que solo puedes tener **un certificado HTTPS por dirección IP**.

     * @param {string} options.cursor – Character to use for cursor, defaults to ▋.
     * @param {Object[]} lineData - Dynamically loaded line data objects.
     * @param {boolean} options.noInit - Don't initialise the animation.
     */
    constructor(container = '#termynal', options = {}) {
        this.container = (typeof container === 'string') ? document.querySelector(container) : container;

    public void test_initialization_idempotency() {
        // Test that multiple init calls are safe
        FileSystemClient client = new FileSystemClient();

        // First initialization
        if (client.isInit.compareAndSet(false, true)) {
            client.init();
        }
        assertTrue("Client should be initialized", client.isInit.get());

        // Second initialization attempt should be no-op

* O TCP não sabe sobre "domínios". Apenas sobre endereços IP.
    * As informações sobre o domínio específico solicitado vão nos dados HTTP.
* Os certificados HTTPS “certificam” um determinado domínio, mas o protocolo e a encriptação acontecem ao nível do TCP, antes de sabermos de que domínio se trata.
* Por padrão, isso significa que você só pode ter um certificado HTTPS por endereço IP.

    return results
```

---

If your application (somehow) doesn't have to communicate with anything else and wait for it to respond, use `async def`, even if you don't need to use `await` inside.

---

If you just don't know, use normal `def`.

---

 * Fix: Use strict timeouts when aborting a download.
 * Fix: Support Shoutcast HTTP responses like `ICY 200 OK`.
 * Fix: Don't unzip if there isn't a response body.
 * Fix: Don't leak gzip streams on redirects.
 * Fix: Don't do DNS lookups on invalid hosts.
 * Fix: Exhaust the underlying stream when reading gzip streams.
 * Fix: Support the `PATCH` method.

But you don't have to worry about them either, incoming dicts are converted automatically and your output is converted automatically to JSON too.

## Bodies of arbitrary `dict`s { #bodies-of-arbitrary-dicts }

You can also declare a body as a `dict` with keys of some type and values of some other type.

    }

    @Override
    public String toString() {
        return this.connection.toString();
    }

    @Override
    public void setDoInput(final boolean doInput) {
        this.connection.setDoInput(doInput);
        this.doInput = doInput;
    }

    @Override
    public boolean getDoInput() {
        return this.connection.getDoInput();
    }

    @Override