* example, thread A may be executing [responseBodyStart] while thread B executes [canceled].
   * Implementations must support such concurrent calls.
   *
   * Note that cancellation is best-effort and that a call may proceed normally after it has been
   * canceled. For example, happy-path events like [requestHeadersStart] and [requestHeadersEnd] may
   * occur after a call is canceled. Typically cancellation takes effect when an expensive I/O

And as most of your logic will now live in its own specific module, the main file will be quite simple.

### Import `FastAPI` { #import-fastapi }

You import and create a `FastAPI` class as normally.

And we can even declare [global dependencies](dependencies/global-dependencies.md) that will be combined with the dependencies for each `APIRouter`:

    FramingSink(
      finished = outFinished,
    )
  internal val readTimeout = StreamTimeout()
  internal val writeTimeout = StreamTimeout()

  /**
   * The reason why this stream was closed, or null if it closed normally or has not yet been
   * closed.
   *
   * If there are multiple reasons to abnormally close this stream (such as both peers closing it
   * near-simultaneously) then this is the first reason known to this peer.
   */

   * @throws NullPointerException if {@code element} is null and this implementation does not permit
   *     null elements. Note that if {@code occurrences} is zero, the implementation may opt to
   *     return normally.
   */
  @CanIgnoreReturnValue
  int add(@ParametricNullness E element, int occurrences);

  /**
   * Adds a single occurrence of the specified element to this multiset.
   *

    NOT_RUN,
    CANCELLED,
    STARTED,
  }

  /**
   * This class helps avoid a StackOverflowError when large numbers of tasks are submitted with
   * {@link MoreExecutors#directExecutor}. Normally, when the first future completes, all the other
   * tasks would be called recursively. Here, we detect that the delegate executor is executing

      Parameter param = params.get(i);
      Object arg = args.get(i);
      // Use new fresh value generator because 'args' were populated with new fresh generator each.
      // Two newFreshValueGenerator() instances should normally generate equal value sequence.
      Object shouldBeEqualArg = generateDummyArg(param, newFreshValueGenerator());
      if (arg != shouldBeEqualArg
          && Objects.equals(arg, shouldBeEqualArg)

      requestBody1.flush()
    }.also { expected ->
      assertThat(expected.message)
        .isEqualTo("stream was reset: CANCEL")
    }
    body1.awaitSuccess()

    // Second duplex request proceeds normally.
    val requestBody2 = (call.request().body as AsyncRequestBody?)!!.takeSink()
    requestBody2.writeUtf8("request body\n")
    requestBody2.close()
    val responseBody2 = response2.body.source()

        /*
         * These classes handle null properly but throw IllegalArgumentException for the default
         * Class argument that this test uses. Normally we'd fix that by declaring a
         * ReflectionFreeAssertThrowsTest with a testNulls method, but that's annoying to have to do
         * for a package-private utility class. So we skip the class entirely instead.
         */

          <version>1.0.0+</version>
          <type>String</type>
          <description>
            The configurator type to use when injecting parameter values into this Mojo. The value is normally deduced
            from the Mojo's implementation language, but can be specified to allow a custom ComponentConfigurator
            implementation to be used.
          </description>
        </field>
        <field>

   * @throws NullPointerException if {@code element} is null and this implementation does not permit
   *     null elements. Note that if {@code occurrences} is zero, the implementation may opt to
   *     return normally.
   */
  @CanIgnoreReturnValue
  int add(@ParametricNullness E element, int occurrences);

  /**
   * Adds a single occurrence of the specified element to this multiset.
   *