FlushResult
Result returned by  FlushAsync call.
                namespace System.IO.Pipelines
{
    public struct FlushResult
    {
        internal ResultFlags _resultFlags;
        public bool IsCanceled => (_resultFlags & ResultFlags.Canceled) != ResultFlags.None;
        public bool IsCompleted => (_resultFlags & ResultFlags.Completed) != ResultFlags.None;
        public FlushResult(bool isCanceled, bool isCompleted)
        {
            _resultFlags = ResultFlags.None;
            if (isCanceled)
                _resultFlags |= ResultFlags.Canceled;
            if (isCompleted)
                _resultFlags |= ResultFlags.Completed;
        }
    }
}