# Learn

Here are the introductory sections and the tutorials to learn **FastAPI**.

    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(

}

android {
  compileSdk = 34

  namespace = "okhttp.android"

  defaultConfig {
    minSdk = 21

    // Make sure to use the AndroidJUnitRunner (or a sub-class) in order to hook in the JUnit 5 Test Builder
    testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"

    buildFeatures {
      buildConfig = false
    }

    testOptions {
      unitTests {

    ```Python hl_lines="20-27"
    {!> ../../../docs_src/schema_extra_example/tutorial003.py!}
    ```

### 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`

You can of course also pass multiple `examples`:

=== "Python 3.10+"

{!../../../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!}

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Because it is installed in the local project, you probably wouldn't be able to call that command directly, but you would put it on your `package.json` file.

It could look like this:

```JSON  hl_lines="7"
{
  "name": "frontend-app",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {

            "Retry-After",
            "1",
          ),
        body = "You took too long!",
        socketPolicy = DisconnectAtEnd,
      ),
    )
    val request = Request(server.url("/"))
    val response = client.newCall(request).execute()
    assertThat(response.body.string()).isEqualTo("You took too long!")
  }

  @Test
  fun requestBodyRetransmittedOnClientRequestTimeout() {

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.
 *

{!../../../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: