had plenty of time as she went down to look about her and to
wonder what was going to happen next.  First, she tried to look
down and make out what she was coming to, but it was too dark to
see anything; then she looked at the sides of the well, and
noticed that they were filled with cupboards and book-shelves;
here and there she saw maps and pictures hung upon pegs.  She
took down a jar from one of the shelves as she passed; it was

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">

had plenty of time as she went down to look about her and to
wonder what was going to happen next.  First, she tried to look
down and make out what she was coming to, but it was too dark to
see anything; then she looked at the sides of the well, and
noticed that they were filled with cupboards and book-shelves;
here and there she saw maps and pictures hung upon pegs.  She
took down a jar from one of the shelves as she passed; it was

    val domainLabelsUtf8Bytes = Array(domainLabels.size) { i -> domainLabels[i].toByteArray() }

    // Start by looking for exact matches. We start at the leftmost label. For example, foo.bar.com
    // will look like: [foo, bar, com], [bar, com], [com]. The longest matching rule wins.
    var exactMatch: String? = null
    for (i in domainLabelsUtf8Bytes.indices) {

    check(latch.await(30, TimeUnit.SECONDS)) { "Timed out waiting for test $number to finish." }
    val endNanos = System.nanoTime()
    val tookMs = TimeUnit.NANOSECONDS.toMillis(endNanos - startNanos.get())
    println("Took ${tookMs}ms")
  }

  private fun getTestCount(): Long {
    val latch = CountDownLatch(1)
    val countRef = AtomicLong()
    val failureRef = AtomicReference<Throwable>()

    newWebSocket(

{!../../../docs_src/custom_request_and_route/tutorial003.py!}
```

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:

```Python hl_lines="13-20"
{!../../../docs_src/custom_request_and_route/tutorial003.py!}

{!../../../docs_src/metadata/tutorial001.py!}
```

!!! tip
    You can write Markdown in the `description` field and it will be rendered in the output.

With this configuration, the automatic API docs would look like:

<img src="/img/tutorial/metadata/image01.png">

## License identifier

Since OpenAPI 3.1.0 and FastAPI 0.99.0, you can also set the `license_info` with an `identifier` instead of a `url`.

For example:

import okio.ByteString.Companion.toByteString

/**
 * Logs SSL keys to a log file, allowing Wireshark to decode traffic and be examined with http2
 * filter. The approach is to hook into JSSE log events for the messages between client and server
 * during handshake, and then take the agreed masterSecret from private fields of the session.
 *

      if (connection.isHealthy(doExtensiveHealthChecks)) return connection

      // In the second synchronized block, release the unhealthy acquired connection. We're also on
      // the hook to close this connection if it's no longer in use.
      val noNewExchangesEvent: Boolean
      val toClose: Socket? =
        connection.withLock {
          noNewExchangesEvent = !connection.noNewExchanges

    All the security utilities that integrate with OpenAPI (and the automatic API docs) inherit from `SecurityBase`, that's how **FastAPI** can know how to integrate them in OpenAPI.

## What it does

It will go and look in the request for that `Authorization` header, check if the value is `Bearer ` plus some token, and will return the token as a `str`.