This includes, for example:

* Email notifications sent after performing an action:
    * As connecting to an email server and sending an email tends to be "slow" (several seconds), you can return the response right away and send the email notification in the background.
* Processing data:

### 3. Example

 *
 * <p>Example usage:</p>
 * <pre>
 * {@code
 * XPathAPI xPathAPI = new XPathAPI();
 * NodeList nodes = xPathAPI.selectNodeList(contextNode, "//example");
 * Node singleNode = xPathAPI.selectSingleNode(contextNode, "//example[1]");
 * XPathEvaluationResult<?> result = xPathAPI.eval(contextNode, "count(//example)");
 * }
 * </pre>
 *

/// note

Notice that, in this case, the `item` that would be taken from the body is optional. As it has a `None` default value.

///

## Multiple body parameters { #multiple-body-parameters }

In the previous example, the *path operations* would expect a JSON body with the attributes of an `Item`, like:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

        String[] sitemaps = new String[] { "http://example.com/sitemap.xml", "http://test.com/sitemap.xml" };
        crawlerContext.addSitemaps(sitemaps);

        // Remove and verify
        String[] removedSitemaps = crawlerContext.removeSitemaps();
        assertNotNull(removedSitemaps);
        assertEquals(2, removedSitemaps.length);
        assertEquals("http://example.com/sitemap.xml", removedSitemaps[0]);

For example, there's an official <a href="https://hub.docker.com/_/python" class="external-link" target="_blank">Python Image</a>.

And there are many other images for different things like databases, for example for:

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>

In all the docs there are examples compatible with each version of Python (when there's a difference).

For example "**Python 3.6+**" means it's compatible with Python 3.6 or above (including 3.7, 3.8, 3.9, 3.10, etc). And "**Python 3.9+**" means it's compatible with Python 3.9 or above (including 3.10, etc).

---

But for this example, we'll use a very simple HTML document with some JavaScript, all inside a long string.

This, of course, is not optimal and you wouldn't use it for production.

In production you would have one of the options above.

But it's the simplest way to focus on the server-side of WebSockets and have a working example:

{* ../../docs_src/websockets/tutorial001.py hl[2,6:38,41:43] *}

* `allow_origin_regex` - Una cadena regex para coincidir con orígenes que deberían estar permitidos para hacer requests cross-origin. por ejemplo, `'https://.*\.example\.org'`.

	Porque estamos usando uma URL relativa, se sua API estava localizada em `https://example.com/`, então irá referir-se à `https://example.com/token`. Mas se sua API estava localizada em `https://example.com/api/v1/`, então irá referir-se à `https://example.com/api/v1/token`.