After you have tests, then you can upgrade the **FastAPI** version to a more recent one, and make sure that all your code is working correctly by running your tests.

If everything is working, or after you make the necessary changes, and all your tests are passing, then you can pin your `fastapi` to that new recent version.

## About Starlette { #about-starlette }

You shouldn't pin the version of `starlette`.

## The normal **FastAPI** app { #the-normal-fastapi-app }

Let's first see how the normal API app would look like before adding the callback.

It will have a *path operation* that will receive an `Invoice` body, and a query parameter `callback_url` that will contain the URL for the callback.

This part is pretty normal, most of the code is probably already familiar to you:

## Query parameter list / multiple values { #query-parameter-list-multiple-values }

When you define a query parameter explicitly with `Query` you can also declare it to receive a list of values, or said in another way, to receive multiple values.

For example, to declare a query parameter `q` that can appear multiple times in the URL, you can write:

description: Suggest an idea for this project
labels: [ "a:feature", "to-triage" ]
assignees: [ ]
body:
  - type: markdown
    attributes:
      value: |
        Please follow the instructions below.
        We receive dozens of issues every week, so to stay productive, we will close issues that don't provide enough information.

        Please open Android-related issues on [the Android Issue Tracker](https://source.android.com/source/report-bugs)

</ul>
<h2>Googlers-Only Links</h2>
<ul>
<li><a href="http://sponge2/$KOKORO_BUILD_ID">Sponge2</a></li>
<li><a href="http://sponge/target:$KOKORO_JOB_NAME">Sponge - recent jobs</a></li>
<li><a href="http://fusion2/ci/kokoro/prod:$(echo "$KOKORO_JOB_NAME" | sed 's!/!%2F!g')">Test Fusion - recent jobs</a></li>
<li><a href="http://cs/f:devtools/kokoro/config/prod/$KOKORO_JOB_NAME">Codesearch - job definition</a></li>

Channel communication is the main method of synchronization
between goroutines.  Each send on a particular channel
is matched to a corresponding receive from that channel,
usually in a different goroutine.
</p>

<p class="rule">
A send on a channel is synchronized before the completion of the
corresponding receive from that channel.
</p>

<p>
This program:
</p>

<pre>
var c = make(chan int, 10)
var a string

     * instead of send/receive.
     *
     * @return threshold in bytes
     */
    int getRdmaReadWriteThreshold();

    /**
     * Get maximum RDMA send size
     *
     * @return max send size in bytes
     */
    int getRdmaMaxSendSize();

    /**
     * Get maximum RDMA receive size
     *
     * @return max receive size in bytes
     */

        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            request = GzipRequest(request.scope, request.receive)
            return await original_route_handler(request)

        return custom_route_handler


app = FastAPI()
app.router.route_class = GzipRoute


@app.post("/sum")

        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            request = GzipRequest(request.scope, request.receive)
            return await original_route_handler(request)

        return custom_route_handler


app = FastAPI()
app.router.route_class = GzipRoute


@app.post("/sum")

     */
    int DEFAULT_RESPONSE_TIMEOUT = 30000;
    /**
     * Default socket timeout in milliseconds.
     */
    int DEFAULT_SO_TIMEOUT = 35000;
    /**
     * Default receive buffer size for SMB transport.
     */
    int DEFAULT_RCV_BUF_SIZE = 0xFFFF;
    /**
     * Default send buffer size for SMB transport.
     */
    int DEFAULT_SND_BUF_SIZE = 0xFFFF;
    /**