And also after the `response` is generated, before returning it.

For example, you could add a custom header `X-Process-Time` containing the time in seconds that it took to process the request and generate a response:

{* ../../docs_src/middleware/tutorial001.py hl[10,12:13] *}

/// tip

In this example, the *path operations* under the `router` will use the custom `TimedRoute` class, and will have an extra `X-Response-Time` header in the response with the time it took to generate the response:

#### The time to answer helps the attackers { #the-time-to-answer-helps-the-attackers }

At that point, by noticing that the server took some microseconds longer to send the "Incorrect username or password" response, the attackers will know that they got _something_ right, some of the initial letters were right.

                        log.debug("Server " + this + " returned zero credits for " + curReq);
                    } else {
                        log.warn("Server " + this + " took away all our credits");
                    }
                } else if (!curReq.isResponseAsync()) {
                    if (log.isTraceEnabled()) {
                        log.trace("Adding credits " + grantedCredits);

{* ../../docs_src/schema_extra_example/tutorial003_an_py310.py hl[22:29] *}

### Example in the docs UI { #example-in-the-docs-ui }

With any of the methods above it would look like this in the `/docs`:

<img src="/img/tutorial/body-fields/image01.png">

### `Body` with multiple `examples` { #body-with-multiple-examples }

You can of course also pass multiple `examples`:

Webargs is a tool that was made to provide that on top of several frameworks, including Flask.

It uses Marshmallow underneath to do the data validation. And it was created by the same developers.

It's a great tool and I have used it a lot too, before having **FastAPI**.

/// info

Webargs was created by the same Marshmallow developers.

You can discover more SDK generators on <a href="https://openapi.tools/#sdk" class="external-link" target="_blank">OpenAPI.Tools</a>.

/// tip

FastAPI automatically generates **OpenAPI 3.1** specifications, so any tool you use must support this version.

///

## SDK Generators from FastAPI Sponsors { #sdk-generators-from-fastapi-sponsors }

This is "synchronous" work, you are "synchronized" with the cashier/cook 👨‍🍳. You have to wait 🕙 and be there at the exact moment that the cashier/cook 👨‍🍳 finishes the burgers and gives them to you, or otherwise, someone else might take them.

<img src="/img/async/parallel-burgers/parallel-burgers-04.png" class="illustration">

### Package Requirements { #package-requirements }

You would normally have the **package requirements** for your application in some file.

It would depend mainly on the tool you use to **install** those requirements.

The most common way to do it is to have a file `requirements.txt` with the package names and their versions, one per line.

/// note

It doesn't matter what you type in the form, it won't work yet. But we'll get there.

///

This is of course not the frontend for the final users, but it's a great automatic tool to document interactively all your API.

It can be used by the frontend team (that can also be yourself).

It can be used by third party applications and systems.