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            Please reopen if you'd like to work on this further.

abstract class EndpointPairIterator<N> extends AbstractIterator<EndpointPair<N>> {
  private final BaseGraph<N> graph;
  private final Iterator<N> nodeIterator;

  @Nullable N node = null; // null is safe as an initial value because graphs don't allow null nodes

  Iterator<N> successorIterator = ImmutableSet.<N>of().iterator();

  static <N> EndpointPairIterator<N> of(BaseGraph<N> graph) {

    int NT_STATUS_OBJECT_PATH_NOT_FOUND = 0xC000003a;
    /** The object path syntax is bad */
    int NT_STATUS_OBJECT_PATH_SYNTAX_BAD = 0xC000003b;
    /** The process cannot access the file because it is being used by another process */
    int NT_STATUS_SHARING_VIOLATION = 0xC0000043;
    /** The file is pending deletion */
    int NT_STATUS_DELETE_PENDING = 0xC0000056;

     *   <li>If this field's value == currentThread, we know that it's up to date, because write
     *       operations in a thread always happen-before subsequent read operations in the same
     *       thread
     *   <li>If this field's value == null because of unsafe publication, we know that it isn't the
     *       object associated with our thread, because if it was the publication wouldn't have been

   * overkill for most Atomics because they are usually irregularly
   * scattered in memory and thus don't interfere much with each
   * other. But Atomic objects residing in arrays will tend to be
   * placed adjacent to each other, and so will most often share
   * cache lines (with a huge negative performance impact) without
   * this precaution.
   *
   * In part because Cells are relatively large, we avoid creating

Because all the **fields actually change** (the type now includes `None` and they now have a default value of `None`), we need to **re-declare** them.

{* ../../docs_src/response_model/tutorial003_02.py hl[8,10:11] *}

This simple case is handled automatically by FastAPI because the return type annotation is the class (or a subclass of) `Response`.

And tools will also be happy because both `RedirectResponse` and `JSONResponse` are subclasses of `Response`, so the type annotation is correct.

### Annotate a Response Subclass { #annotate-a-response-subclass }

<img src="/img/tutorial/sub-applications/image02.png">

If you try interacting with any of the two user interfaces, they will work correctly, because the browser will be able to talk to each specific app or sub-app.

### Technical Details: `root_path` { #technical-details-root-path }

   * already complete, we would not initialize the subclass before calling {@link
   * #collectValueFromNonCancelledFuture}. As this is called after the subclass is constructed,
   * we're guaranteed to have properly initialized the subclass.
   */
  final void init() {
    /*

        }
    }

    private void handleChecksumFailure(String checksumPolicy, String message, Throwable cause)
            throws ChecksumFailedException {
        if (ArtifactRepositoryPolicy.CHECKSUM_POLICY_FAIL.equals(checksumPolicy)) {
            throw new ChecksumFailedException(message, cause);
        } else if (!ArtifactRepositoryPolicy.CHECKSUM_POLICY_IGNORE.equals(checksumPolicy)) {