///

### Étape 2 : créer une "instance" `FastAPI`

{* ../../docs_src/first_steps/tutorial001.py hl[3] *}

Ici la variable `app` sera une "instance" de la classe `FastAPI`.

Ce sera le point principal d'interaction pour créer toute votre API.

Cette `app` est la même que celle à laquelle fait référence `uvicorn` dans la commande :

<div class="termy">

```console

## `Union` ou `anyOf` { #union-or-anyof }

Você pode declarar uma resposta como o `Union` de dois ou mais tipos, o que significa que a resposta seria qualquer um deles.

Isso será definido no OpenAPI com `anyOf`.

 * This class provides functionality to handle pagination of failed crawler URLs
 * with search filters and navigation capabilities.
 */
public class FailureUrlPager implements Serializable {

    /** Serial version UID for serialization compatibility. */
    private static final long serialVersionUID = 1L;

    /**
     * Default constructor.
     */
    public FailureUrlPager() {
        // Default constructor
    }

   * tasks. Second, the returned list will always be empty, as any submitted task is considered to
   * have started execution. This applies also to tasks given to {@code invokeAll} or {@code
   * invokeAny} which are pending serial execution, even the subset of the tasks that have not yet
   * started execution. It is unclear from the {@code ExecutorService} specification if these should

 * ClassToInstanceMap}</a>.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible
@SuppressWarnings("serial") // using writeReplace instead of standard serialization
public final class MutableClassToInstanceMap<B extends @Nullable Object>
    extends ForwardingMap<Class<? extends @NonNull B>, B>

        Thread.currentThread().interrupt();
      }
    }
    return added;
  }

  /**
   * Returns a synchronized (thread-safe) queue backed by the specified queue. In order to guarantee
   * serial access, it is critical that <b>all</b> access to the backing queue is accomplished
   * through the returned queue.
   *
   * <p>It is imperative that the user manually synchronize on the returned queue when accessing the

    * Puisque le paramètre `q` est déclaré avec `= None`, il est facultatif.
    * Sans le `None`, il serait nécessaire (comme l'est <abbr title="en anglais : body">le corps</abbr> de la requête dans le cas du `PUT`).

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@link PeekingIterator}.
 *
 * @author Mick Killianey
 */
@SuppressWarnings("serial") // No serialization is used in this test
@GwtCompatible
@NullMarked
public class PeekingIteratorTest extends TestCase {

  /**

    * Doğrulayıcılar en kompleks data şemalarının bile temiz ve kolay bir şekilde tanımlanmasına izin veriyor, ve hepsi JSON şeması olarak dokümante ediliyor
    * Pydantic, JSON objen ne kadar derin (nested) olursa olsun doğrulamasını ve gösterimini yapıyor
* **Genişletilebilir**:

import org.jspecify.annotations.Nullable;

/**
 * GWT emulated version of {@link com.google.common.collect.ImmutableList}. TODO(cpovirk): more doc
 *
 * @author Hayward Chan
 */
@SuppressWarnings("serial") // we're overriding default serialization
public abstract class ImmutableList<E> extends ImmutableCollection<E>
    implements List<E>, RandomAccess {

  ImmutableList() {}