gistfile1.txt

                Task flushingTask = null;
                
                public override Task FlushAsync(CancellationToken cancellationToken)
                {
                    Interlocked.CompareExchange(
                        ref flushingTask,
                        Task.Delay(200, cancellationToken).ContinueWith(
                            async (t) =>
                            {
                                await write.FlushAsync(cancellationToken);
                                Interlocked.Exchange(ref flushingTask, null);
                            },
                            cancellationToken),
                        null);
                    return Task.FromResult(true);
                }