* **Uvicorn**:
    * Will have the best performance, as it doesn't have much extra code apart from the server itself.

  //
  // - @PolyNull means "@Nullable or @Nonnull"
  //   (That would be unsound for an input Iterable<@Nullable Foo>. So, if we wanted to use
  //   @PolyNull, we would have to restrict this method to non-null <T>. But it has users who pass
  //   iterables with null elements.)
  //
  // - @JointlyNullable means "@Nullable or no annotation"
  @CheckForNull

 */
/*
 * Some of the annotations below were added after we released our separate
 * com.google.guava:listenablefuture:1.0 artifact. (For more on that artifact, see
 * https://github.com/google/guava/releases/tag/v27.0) This means that the copy of ListenableFuture
 * in com.google.guava:guava differs from the "frozen" copy in the listenablefuture artifact. This
 * could in principle cause problems for some users. Still, we expect that the benefits of the

 */
/*
 * Some of the annotations below were added after we released our separate
 * com.google.guava:listenablefuture:1.0 artifact. (For more on that artifact, see
 * https://github.com/google/guava/releases/tag/v27.0) This means that the copy of ListenableFuture
 * in com.google.guava:guava differs from the "frozen" copy in the listenablefuture artifact. This
 * could in principle cause problems for some users. Still, we expect that the benefits of the

```Python hl_lines="9  15-16  19-20  23-24"
{!> ../../docs_src/extra_models/tutorial002.py!}
```

////

## `Union` or `anyOf`

You can declare a response to be the `Union` of two or more types, that means, that the response would be any of them.

It will be defined in OpenAPI with `anyOf`.

	// Make subtype to avoid recursive UnmarshalXML().
	type config Config
	parsedConfig := config{}
	if err := d.DecodeElement(&parsedConfig, &start); err != nil {
		return err
	}

	// Empty queue list means user wants to delete the notification configuration.
	if len(parsedConfig.QueueList) > 0 {
		for i, q1 := range parsedConfig.QueueList[:len(parsedConfig.QueueList)-1] {
			for _, q2 := range parsedConfig.QueueList[i+1:] {

      // SequentialExecutor by the time the barrier is satisfied
      barrier.await(1, SECONDS);
      executor.execute(barrierTask);
      // timeout means the second task wasn't even tried
      barrier.await(1, SECONDS);
    } finally {
      service.shutdown();
    }
  }

  public void testRejectedExecutionThrownWithMultipleCalls() throws Exception {

  // UID is an identifier for the individual request/response. It allows us to distinguish instances of requests which are
  // otherwise identical (parallel requests, requests when earlier requests did not modify etc)
  // The UID is meant to track the round trip (request/response) between the KAS and the WebHook, not the user request.
  // It is suitable for correlating log entries between the webhook and apiserver, for either auditing or debugging.

  // UID is an identifier for the individual request/response. It allows us to distinguish instances of requests which are
  // otherwise identical (parallel requests, requests when earlier requests did not modify etc)
  // The UID is meant to track the round trip (request/response) between the KAS and the WebHook, not the user request.
  // It is suitable for correlating log entries between the webhook and apiserver, for either auditing or debugging.

  // +optional
  repeated string resources = 3;

  // ResourceNames is an optional white list of names that the rule applies to.  An empty set means that everything is allowed.
  // +optional
  repeated string resourceNames = 4;

  // NonResourceURLs is a set of partial urls that a user should have access to.  *s are allowed, but only as the full, final step in the path