* Copies all characters between the {@link Readable} and {@link Appendable} objects. Does not
   * close or flush either object.
   *
   * @param from the object to read from
   * @param to the object to write to
   * @return the number of characters copied
   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue
  public static long copy(Readable from, Appendable to) throws IOException {

        return in.read(cbuf, off, Math.max(len - 1024, 0));
      }
    };
  }

  /** Wrap an appendable in an appendable to defeat any type specific optimizations. */
  private static Appendable wrapAsGenericAppendable(final Appendable a) {
    return new Appendable() {

      @Override
      public Appendable append(CharSequence csq) throws IOException {
        a.append(csq);
        return this;
      }

        return in.read(cbuf, off, Math.max(len - 1024, 0));
      }
    };
  }

  /** Wrap an appendable in an appendable to defeat any type specific optimizations. */
  private static Appendable wrapAsGenericAppendable(final Appendable a) {
    return new Appendable() {

      @Override
      public Appendable append(CharSequence csq) throws IOException {
        a.append(csq);
        return this;
      }

   * Does not close {@code appendable} if it is {@code Closeable}.
   *
   * @return the number of characters copied
   * @throws IOException if an I/O error occurs while reading from this source or writing to {@code
   *     appendable}
   */
  @CanIgnoreReturnValue
  public long copyTo(Appendable appendable) throws IOException {

      throw new AssertionError(e);
    }
  }

  private static final Appendable NASTY_APPENDABLE =
      new Appendable() {
        @Override
        public Appendable append(@Nullable CharSequence csq) throws IOException {
          throw new IOException();
        }

        @Override
        public Appendable append(@Nullable CharSequence csq, int start, int end)
            throws IOException {

  private static class SpyAppendable implements Appendable, Flushable, Closeable {
    boolean flushed;
    boolean closed;
    StringBuilder result = new StringBuilder();

    @Override
    public Appendable append(CharSequence csq) {
      result.append(csq);
      return this;
    }

    @Override
    public Appendable append(char c) {
      result.append(c);
      return this;
    }

      }
    };
  }

  static Appendable separatingAppendable(
      Appendable delegate, String separator, int afterEveryChars) {
    checkNotNull(delegate);
    checkNotNull(separator);
    checkArgument(afterEveryChars > 0);
    return new Appendable() {
      int charsUntilSeparator = afterEveryChars;

      @Override
      public Appendable append(char c) throws IOException {

Utiliser `BackgroundTasks` fonctionne aussi avec le système d'injection de dépendances. Vous pouvez déclarer un paramètre de type `BackgroundTasks` à différents niveaux : dans une *fonction de chemin*, dans une dépendance, dans une sous-dépendance...

**FastAPI** sait quoi faire dans chaque cas et comment réutiliser le même objet, afin que tous les paramètres de type `BackgroundTasks` soient fusionnés et que les tâches soient exécutées en arrière-plan :

After checking all these things and ensuring the PR has the right labels, you can merge it.

## Dependabot PRs

Dependabot will create PRs to update dependencies for several things, and those PRs all look similar, but some are way more delicate than others.

* ⬆ Bump dawidd6/action-download-artifact from 2.9.0 to 2.21.1. PR [#5130](https://github.com/tiangolo/fastapi/pull/5130) by [@dependabot[bot]](https://github.com/apps/dependabot).
* ⬆ Bump actions/setup-python from 2 to 4. PR [#5129](https://github.com/tiangolo/fastapi/pull/5129) by [@dependabot[bot]](https://github.com/apps/dependabot).