/**
   * charBuffer holds characters that have been read from the Reader but not encoded yet. The buffer
   * is perpetually "flipped" (unencoded characters between position and limit).
   */
  private CharBuffer charBuffer;

  /**
   * byteBuffer holds encoded characters that have not yet been sent to the caller of the input
   * stream. When encoding it is "unflipped" (encoded bytes between 0 and position) and when

  /**
   * charBuffer holds characters that have been read from the Reader but not encoded yet. The buffer
   * is perpetually "flipped" (unencoded characters between position and limit).
   */
  private CharBuffer charBuffer;

  /**
   * byteBuffer holds encoded characters that have not yet been sent to the caller of the input
   * stream. When encoding it is "unflipped" (encoded bytes between 0 and position) and when

    assertFalse(fakePool.hasNext());
    e.execute(intCounter);
    // A task should have been scheduled
    assertTrue(fakePool.hasNext());
    e.execute(intCounter);
    // Our executor hasn't run any tasks yet.
    assertEquals(0, totalCalls.get());
    fakePool.runAll();
    assertEquals(2, totalCalls.get());
    // Queue is empty so no runner should be scheduled.
    assertFalse(fakePool.hasNext());

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[22] *}

/// tip

All this might seem contrived. And it might not be very clear how is it useful yet.

These examples are intentionally simple, but show how it all works.

In the chapters about security, there are utility functions that are implemented in this same way.

          annotationClass.getDeclaringClass(),
          returnType.getComponentType());
    }
  }

  // This is public so that tests for Feature enums we haven't yet imagined
  // can reuse it.
  public static <E extends Enum<?> & Feature<?>> void assertGoodFeatureEnum(
      Class<E> featureEnumClass) {
    final Class<?>[] classes = featureEnumClass.getDeclaredClasses();

          annotationClass.getDeclaringClass(),
          returnType.getComponentType());
    }
  }

  // This is public so that tests for Feature enums we haven't yet imagined
  // can reuse it.
  public static <E extends Enum<?> & Feature<?>> void assertGoodFeatureEnum(
      Class<E> featureEnumClass) {
    final Class<?>[] classes = featureEnumClass.getDeclaredClasses();

    }

    // ===================================================================================================
    /**
     * Helper class to traverse graph. Required to make the containing method thread-safe
     * and yet use class level data to lessen stack usage in recursion
     */
    private class ClasspathGraphVisitor {
        MetadataGraph graph;

        ClasspathContainer cpc;

        List<MetadataGraphVertex> visited;

 *   <li>Loading: loading is pending
 * </ul>
 *
 * <p>Invalid:
 *
 * <ul>
 *   <li>Expired: time expired (key/value may still be set)
 *   <li>Collected: key/value was partially collected, but not yet cleaned up
 *   <li>Unset: marked as unset, awaiting cleanup or reuse
 * </ul>
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
interface ReferenceEntry<K, V> {
  /** Returns the value reference from this entry. */

   *     sure you are passing the two parameters in the right order.
   * @param actual The type that the formal type variable(s) are mapped to. It can be or contain yet
   *     other type variables, in which case these type variables will be further resolved if
   *     corresponding mappings exist in the current {@code TypeResolver} instance.
   */

///

## Returning a custom `Response`

The example above shows all the parts you need, but it's not very useful yet, as you could have just returned the `item` directly, and **FastAPI** would put it in a `JSONResponse` for you, converting it to a `dict`, etc. All that by default.

Now, let's see how you could use that to return a custom response.