* thought of as overkill; however, it's difficult to determine which proper subset of this massive
 * set would be sufficient to expose any possible bug. Brute force is simpler.
 *
 * <p>To use this class the concrete subclass must implement the {@link
 * IteratorTester#newTargetIterator()} method. This is because it's impossible to test an Iterator
 * without changing its state, so the tester needs a steady supply of fresh Iterators.
 *

   * {@linkplain Object#equals equal} to the original, nor is it required to return even an object
   * of the same class. For example, if sublists of {@code MyList} instances were serializable,
   * those sublists might implement a private {@code MySubList} type but serialize as a plain {@code
   * MyList} to save space. So long as {@code MyList} has all the public supertypes of {@code

import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * Base class for services that do not need a thread while "running" but may need one during startup
 * and shutdown. Subclasses can implement {@link #startUp} and {@link #shutDown} methods, each which
 * run in an executor which by default uses a separate thread for each method.
 *
 * @author Chris Nokleberg
 * @since 1.0
 */
@GwtIncompatible

    }

    /**
     * Determines whether the current request is authorized to access the API endpoint.
     * This default implementation returns false, requiring subclasses to override
     * and implement proper access control logic.
     *
     * @return true if access is allowed, false otherwise
     */
    protected boolean isAccessAllowed() {
        return false;
    }

      }
    };

    public abstract Queue<Integer> create(Comparator<Integer> comparator);
  }

  /**
   * Does a CPU intensive operation on Integer and returns a BigInteger Used to implement an
   * ordering that spends a lot of cpu.
   */
  static class ExpensiveComputation implements Function<Integer, BigInteger> {
    @Override
    public BigInteger apply(Integer from) {

      }
    };

    public abstract Queue<Integer> create(Comparator<Integer> comparator);
  }

  /**
   * Does a CPU intensive operation on Integer and returns a BigInteger Used to implement an
   * ordering that spends a lot of cpu.
   */
  static class ExpensiveComputation implements Function<Integer, BigInteger> {
    @Override
    public BigInteger apply(Integer from) {

import java.util.concurrent.ExecutionException;

/**
 * This class provides a skeletal implementation of the {@code Cache} interface to minimize the
 * effort required to implement this interface.
 *
 * <p>To implement a cache, the programmer needs only to extend this class and provide an
 * implementation for the {@link #put} and {@link #getIfPresent} methods. {@link #getAllPresent} is

{* ../../docs_src/sub_applications/tutorial001_py310.py hl[3, 6:8] *}

### Sous-application { #sub-application }

Ensuite, créez votre sous‑application et ses *chemins d'accès*.

Cette sous‑application est simplement une autre application FastAPI standard, mais c'est celle qui sera « montée » :

{* ../../docs_src/sub_applications/tutorial001_py310.py hl[11, 14:16] *}

### Monter la sous-application { #mount-the-sub-application }

    * Un exemple est `404`, pour une réponse « Non trouvé ».
    * Pour des erreurs génériques du client, vous pouvez simplement utiliser `400`.

Mais si vous avez besoin d'accéder aux variables et objets de la même application **FastAPI**, ou si vous avez besoin d'effectuer de petites tâches d'arrière-plan (comme envoyer des notifications par email), vous pouvez simplement vous contenter d'utiliser `BackgroundTasks`.

## Résumé { #recap }