Let's start with an example and then see it in detail.

We create an async function `lifespan()` with `yield` like this:

{* ../../docs_src/events/tutorial003_py310.py hl[16,19] *}

        assertNotNull(retrieved);
        assertEquals(engine, retrieved);
    }

    // Test concurrent-like scenario (sequential but simulating concurrent behavior)
    @Test
    public void test_add_multipleSameNameSequential() {
        TestScriptEngine engine1 = new TestScriptEngine("v1");
        TestScriptEngine engine2 = new TestScriptEngine("v2");

  /** JavaLangAccess class name to load using reflection */
  @J2ktIncompatible @GwtIncompatible // not used by GWT emulation
  private static final String JAVA_LANG_ACCESS_CLASSNAME = "sun.misc.JavaLangAccess";

  /** SharedSecrets class name to load using reflection */
  @J2ktIncompatible
  @GwtIncompatible // not used by GWT emulation
  @VisibleForTesting
  static final String SHARED_SECRETS_CLASSNAME = "sun.misc.SharedSecrets";

Symmetrically, interceptors can rewrite response headers and transform the response body. This is generally more dangerous than rewriting request headers because it may violate the webserver's expectations!

If you're in a tricky situation and prepared to deal with the consequences, rewriting response headers is a powerful way to work around problems. For example, you can fix a server's misconfigured `Cache-Control` response header to enable better response caching:

// RELEASE.2018-03-16T22-52-12Z after migrating v1 to v2 to v3. This
// migration failed to capture '.This' field properly which indicates
// the disk UUID association. Below error message is returned when
// we see this situation in format.json, for more info refer
// https://github.com/minio/minio/issues/5667
var errErasureV3ThisEmpty = fmt.Errorf("Erasure format version 3 has This field empty")

        } finally {
            ComponentUtil.setFessConfig(null);
        }
    }

    @Test
    public void test_isTarget_withMultipleConditions() {
        // Test isTarget with multiple MIME type patterns (simulating real config)
        generator = new TestThumbnailGenerator();

        FessConfig mockConfig = new FessConfig.SimpleImpl() {
            @Override
            public String getIndexFieldThumbnail() {

   * {@link IllegalArgumentException} if passed a {@code toElement} greater than an earlier {@code
   * toElement}. However, this method doesn't throw an exception in that situation, but instead
   * keeps the original {@code toElement}.
   */
  @Override
  public ImmutableSortedSet<E> headSet(E toElement) {
    return headSet(toElement, false);
  }

  /**
   * @since 12.0

    // should be reading the byte at index 10.
    // We could use a custom InputStream instead to make the read start at index 10, but since this
    // is a racy situation anyway, this behavior seems reasonable.
    assertEquals(-1, in.read());
  }

  private static class AppendableByteSource extends ByteSource {
    private byte[] bytes;

        boolean deleted = Files.deleteIfExists(tempFile);
        assertFalse(deleted);
    }

    @Test
    public void test_atomicDeleteIfExists_concurrentScenario() throws Exception {
        // Test simulating concurrent access scenario
        Path tempDir = Files.createTempDirectory("concurrent_test");
        try {
            Path targetFile = tempDir.resolve("target.tmp");
            Files.createFile(targetFile);

Plusieurs d'entre eux sont explorés dans les prochains chapitres du tutoriel.

## L'ordre importe { #order-matters }

Quand vous créez des *chemins d'accès*, vous pouvez vous retrouver dans une situation avec un chemin fixe.

Par exemple `/users/me`, disons pour récupérer les données de l'utilisateur actuel.