assertEquals(string, readFully(reader));
    assertFullyRead(reader);

    // reset, skip, mark, then read the rest
    reader.reset();
    assertEquals(5, reader.skip(5));
    reader.mark(Integer.MAX_VALUE);
    assertEquals(string.substring(5), readFully(reader));
    assertFullyRead(reader);

    // reset to the mark and then read the rest
    reader.reset();
    assertEquals(string.substring(5), readFully(reader));

    return true;
  }

  @Override
  public synchronized void mark(int readAheadLimit) throws IOException {
    checkArgument(readAheadLimit >= 0, "readAheadLimit (%s) may not be negative", readAheadLimit);
    checkOpen();
    mark = pos;
  }

  @Override
  public synchronized void reset() throws IOException {
    checkOpen();
    pos = mark;
  }

  @Override

    return true;
  }

  @Override
  public synchronized void mark(int readAheadLimit) throws IOException {
    checkArgument(readAheadLimit >= 0, "readAheadLimit (%s) may not be negative", readAheadLimit);
    checkOpen();
    mark = pos;
  }

  @Override
  public synchronized void reset() throws IOException {
    checkOpen();
    pos = mark;
  }

  @Override

    assertThat(expected).hasMessageThat().isEqualTo("Mark not set");
  }

  public void testMarkNotSupported() {
    counter = new CountingInputStream(new UnmarkableInputStream());

    IOException expected = assertThrows(IOException.class, () -> counter.reset());
    assertThat(expected).hasMessageThat().isEqualTo("Mark not supported");
  }

  TFE_OpReset(reused_op.get(), "Identity",
              "/job:localhost/replica:0/task:0/device:CPU:0", status.get());
  ASSERT_TRUE(TF_GetCode(status.get()) == TF_OK) << TF_Message(status.get());
  ASSERT_EQ(tensorflow::string(TFE_OpGetDevice(reused_op.get(), status.get())),
            tensorflow::string("/job:localhost/replica:0/task:0/device:CPU:0"));
  ASSERT_TRUE(TF_GetCode(status.get()) == TF_OK) << TF_Message(status.get());
}

  static void clear(Buffer b) {
    b.clear();
  }

  static void flip(Buffer b) {
    b.flip();
  }

  static void limit(Buffer b, int limit) {
    b.limit(limit);
  }

  static void mark(Buffer b) {
    b.mark();
  }

  static void position(Buffer b, int position) {
    b.position(position);
  }

  static void reset(Buffer b) {
    b.reset();
  }

  private Java8Compatibility() {}

   * running with have the given name.
   *
   * @param task The Runnable to wrap
   * @param nameSupplier The supplier of thread names, {@link Supplier#get get} will be called once
   *     for each invocation of the wrapped callable.
   */
  @J2ktIncompatible
  @GwtIncompatible // threads
  static Runnable threadRenaming(Runnable task, Supplier<String> nameSupplier) {
    checkNotNull(nameSupplier);

// on each underlying device.
//
// For example if `device_name` is
//   "/job:localhost/replica:0/task:0/device:CUSTOM:0"
// and `underlying_devices` is
//   {"/job:localhost/replica:0/task:0/device:GPU:0",
//    "/job:localhost/replica:0/task:0/device:GPU:1"}
// Then executing an operation on CUSTOM:0 will execute it on GPU:0 and GPU:1.
//

// custom devices will fail.
//
// `device_name` must not name an existing physical or custom device. It must
// follow the format:
//
//    /job:<name>/replica:<replica>/task:<task>/device:<type>:<device_num>
//
// If the device is successfully registered, `status` is set to TF_OK. Otherwise
// the device is not usable. In case of a bad status, `device.delete_device` is

    }

    /**
     * Mark a project as required and activated.
     * @param selector The selector of the project.
     */
    public void activateRequiredProject(String selector) {
        this.activations.add(new ProjectActivationSettings(selector, ActivationSettings.ACTIVATION_REQUIRED));
    }

    /**
     * Mark a project as optional and activated.