public async static Task Test(CognitoAWSCredentials credentials)
    {
        SemaphoreSlim concurrencySemaphore = new SemaphoreSlim(10);
        List<Task> taskList = new List<Task>();

        AmazonS3Config config = new AmazonS3Config();
        config.RegionEndpoint = Amazon.RegionEndpoint.USEast1;

        AmazonS3Client client = new AmazonS3Client(credentials, config);

        foreach (string key in _fileNames) //_fileNames is an array of 320 S3 keys
        {
            await concurrencySemaphore.WaitAsync();

            Task task = Task.Run(
                async () =>
                {
                    byte[] trash;
                    try
                    {
                        Trace.Message("S3: Downloading key '" + key + "'");

                        GetObjectRequest request = new GetObjectRequest()
                        {
                            BucketName = "LucentWearDesigns",
                            Key = key
                        };

                        using (GetObjectResponse response = await client.GetObjectAsync(request))
                        {
                            using (BinaryReader reader = new BinaryReader(response.ResponseStream))
                            {
                                // Read data
                                int length = (int)response.ContentLength;

                                trash = reader.ReadBytes(length);
                            }
                        }
                    }
                    catch (Exception x)
                    {
                        Trace.Message("S3: error downloading key: " + key);
                        Trace.Message(x.Message);
                        Trace.Message(x.StackTrace);
                        throw;
                    }
                    finally
                    {
                        concurrencySemaphore.Release();
                    }

                });

            taskList.Add(task);
        }

        //Wait until all are finished
        await Task.WhenAll(taskList);
        Trace.Message("Synch: Success");
    }