* Futures.FutureCombiner#callAsync(AsyncCallable, java.util.concurrent.Executor)}.
 *
 * <p>Much like {@link java.util.concurrent.Callable}, but returning a {@link ListenableFuture}
 * result.
 *
 * @since 20.0
 */
@GwtCompatible
public interface AsyncCallable<V extends @Nullable Object> {
  /**

    return () -> value;
  }

  /**
   * Creates an {@link AsyncCallable} from a {@link Callable}.
   *
   * <p>The {@link AsyncCallable} returns the {@link ListenableFuture} resulting from {@link
   * ListeningExecutorService#submit(Callable)}.
   *
   * @since 20.0
   */
  @J2ktIncompatible
  @GwtIncompatible
  public static <T extends @Nullable Object> AsyncCallable<T> asAsyncCallable(

    String expected = "MyCallableString";
    Callable<String> callable = () -> expected;

    AsyncCallable<String> asyncCallable =
        Callables.asAsyncCallable(callable, newDirectExecutorService());

    ListenableFuture<String> future = asyncCallable.call();
    assertThat(future.get()).isEqualTo(expected);
  }

  @J2ktIncompatible
  @GwtIncompatible

    String expected = "MyCallableString";
    Callable<String> callable = () -> expected;

    AsyncCallable<String> asyncCallable =
        Callables.asAsyncCallable(callable, newDirectExecutorService());

    ListenableFuture<String> future = asyncCallable.call();
    assertThat(future.get()).isEqualTo(expected);
  }

  @J2ktIncompatible
  @GwtIncompatible

   * callable} or a callable that has begun to execute, but if the output future is cancelled before
   * {@link AsyncCallable#call()} is invoked, {@link AsyncCallable#call()} will not be invoked.
   */
  public <T extends @Nullable Object> ListenableFuture<T> submitAsync(
      AsyncCallable<T> callable, Executor executor) {
    checkNotNull(callable);
    checkNotNull(executor);

    }
  }

  @WeakOuter
  private final class TrustedFutureInterruptibleAsyncTask
      extends InterruptibleTask<ListenableFuture<V>> {
    private final AsyncCallable<V> callable;

    TrustedFutureInterruptibleAsyncTask(AsyncCallable<V> callable) {
      this.callable = checkNotNull(callable);
    }

    @Override
    final boolean isDone() {
      return TrustedListenableFutureTask.this.isDone();

  }

  @WeakOuter
  private final class AsyncCallableInterruptibleTask
      extends CombinedFutureInterruptibleTask<ListenableFuture<V>> {
    private final AsyncCallable<V> callable;

    AsyncCallableInterruptibleTask(AsyncCallable<V> callable, Executor listenerExecutor) {
      super(listenerExecutor);
      this.callable = checkNotNull(callable);
    }

    @Override

    @SuppressWarnings("AnonymousToLambda") // We want an instance that can be GCed.
    AsyncCallable<Long> combiner =
        new AsyncCallable<Long>() {
          @Override
          public ListenableFuture<Long> call() {
            return SettableFuture.create();
          }
        };
    WeakReference<AsyncCallable<Long>> combinerRef = new WeakReference<>(combiner);

    ListenableFuture<Long> unused =

    @SuppressWarnings("AnonymousToLambda") // We want an instance that can be GCed.
    AsyncCallable<Long> combiner =
        new AsyncCallable<Long>() {
          @Override
          public ListenableFuture<Long> call() {
            return SettableFuture.create();
          }
        };
    WeakReference<AsyncCallable<Long>> combinerRef = new WeakReference<>(combiner);

    ListenableFuture<Long> unused =

   *
   * @throws RejectedExecutionException if the task cannot be scheduled for execution
   * @since 23.0
   */
  public static <O extends @Nullable Object> ListenableFuture<O> submitAsync(
      AsyncCallable<O> callable, Executor executor) {
    TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
    executor.execute(task);
    return task;
  }

  /**