Request
        .Builder()
        .url(url)
        .build()

    val promise = CompletableFuture<Response>()

    val call = client.newCall(request)
    call.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          promise.completeExceptionally(e)
        }

        override fun onResponse(

    headersDelayAmount = delay
    headersDelayUnit = unit
  }

  fun getHeadersDelay(unit: TimeUnit): Long = unit.convert(headersDelayAmount, headersDelayUnit)

  fun withPush(promise: PushPromise) =
    apply {
      promises.add(promise)
    }

  fun withSettings(settings: Settings) =
    apply {
      this.settings = settings
    }

  fun withWebSocketUpgrade(listener: WebSocketListener) =

        flags = FLAG_ACK,
      )
      sink.flush()
    }
  }

  /**
   * HTTP/2 only. Send a push promise header block.
   *
   * A push promise contains all the headers that pertain to a server-initiated request, and a
   * `promisedStreamId` to which response frames will be delivered. Push promise frames are sent as
   * a part of the response to `streamId`. The `promisedStreamId` has a priority of one greater than

       * we're copying into a `contents` array whose type allows it to contain nulls. Still, it's
       * worth noting that we promise not to put nulls into the array in the first `size` elements.
       * We uphold that promise here because our callers promise that `elements` will not contain
       * nulls in its first `n` elements.
       */
      System.arraycopy(elements, 0, contents, size, n);
      size += n;

    /**
     * When [protocols][MockWebServer.protocols] include [HTTP_2][okhttp3.Protocol], this attaches a
     * pushed stream to this response.
     */
    public fun addPush(promise: PushPromise): Builder =
      apply {
        this.pushPromises_ += promise
      }

    /**
     * When [protocols][MockWebServer.protocols] include [HTTP_2][okhttp3.Protocol], this pushes
     * [settings] before writing the response.
     */

  private val writerQueue = taskRunner.newQueue()

  /** Ensures push promise callbacks events are sent in order per stream. */
  private val pushQueue = taskRunner.newQueue()

  /** Notifies the listener of settings changes. */
  private val settingsListenerQueue = taskRunner.newQueue()

  /** User code to run in response to push promise events. */
  private val pushObserver: PushObserver = builder.pushObserver

        Header(Header.TARGET_SCHEME, "https"),
        Header(Header.TARGET_AUTHORITY, "squareup.com"),
        Header(Header.TARGET_PATH, "/"),
      )

    // Write the push promise frame, specifying the associated stream ID.
    val headerBytes = literalHeaders(pushPromise)
    writeMedium(frame, (headerBytes.size + 4).toInt())
    frame.writeByte(Http2.TYPE_PUSH_PROMISE)

            // callable actually completes. (We could detect completion in our wrapper
            // `AsyncCallable task`.) However, our contract also promises:
            //
            // 2. not to cancel any Future the user returned from an AsyncCallable
            //
            // We promise this because, once we cancel that Future, we would no longer be able to

  }

  public void testPowerSetIteration_manual() {
    ImmutableSet<Integer> elements = ImmutableSet.of(1, 2, 3);
    Set<Set<Integer>> powerSet = powerSet(elements);
    // The API doesn't promise this iteration order, but it's convenient here.
    Iterator<Set<Integer>> i = powerSet.iterator();
    assertEquals(ImmutableSet.of(), i.next());
    assertEquals(ImmutableSet.of(1), i.next());

      if (bytesRemaining == 0L) return -1

      val read = super.read(sink, minOf(bytesRemaining, byteCount))
      if (read == -1L) {
        carrier.noNewExchanges() // The server didn't supply the promised content length.
        val e = ProtocolException("unexpected end of stream")
        responseBodyComplete(TRAILERS_RESPONSE_BODY_TRUNCATED)
        throw e
      }

      bytesRemaining -= read