System.IO.FileStream.TaskFromResultOrCache C# (CSharp) Method

        private Task<int> TaskFromResultOrCache(int result)
        {
            Task<int> completedTask = _lastSynchronouslyCompletedTask;
            Debug.Assert(completedTask == null || completedTask.Status == TaskStatus.RanToCompletion, "Cached task should have completed successfully");

            if ((completedTask == null) || (completedTask.Result != result))
            {
                completedTask = Task.FromResult(result);
                _lastSynchronouslyCompletedTask = completedTask;
            }

            return completedTask;
        }