Amazon.S3.Util.AmazonS3Util.DoesS3BucketExistAsync C# (CSharp) Method

        public static async System.Threading.Tasks.Task<bool> DoesS3BucketExistAsync(IAmazonS3 s3Client, string bucketName)
        {
            if (s3Client == null)
            {
                throw new ArgumentNullException("s3Client", "The s3Client cannot be null!");
            }

            if (String.IsNullOrEmpty(bucketName))
            {
                throw new ArgumentNullException("bucketName", "The bucketName cannot be null or the empty string!");
            }

            var request = new GetPreSignedUrlRequest
            {
                BucketName = bucketName,
                Expires = DateTime.Now.AddDays(1),
                Verb = HttpVerb.HEAD,
                Protocol = Protocol.HTTP
            };

            var url = s3Client.GetPreSignedURL(request);
            var uri = new Uri(url);

            var httpRequest = WebRequest.Create(uri) as HttpWebRequest;
            httpRequest.Method = "HEAD";
            var concreteClient = s3Client as AmazonS3Client;
            if (concreteClient != null)
            {

                concreteClient.ConfigureProxy(httpRequest);
            }

            try
            {
#if PCL
                var result = httpRequest.BeginGetResponse(null, null);
                using (var httpResponse = httpRequest.EndGetResponse(result) as HttpWebResponse)
#else 
                using (var httpResponse = await httpRequest.GetResponseAsync().ConfigureAwait(false) as HttpWebResponse)
#endif          
                {
                    // If all went well, the bucket was found!
                    return true;
                }
            }
            catch (WebException we)
            {
                using (var errorResponse = we.Response as HttpWebResponse)
                {
                    if (errorResponse != null)
                    {
                        var code = errorResponse.StatusCode;
                        return code != HttpStatusCode.NotFound &&
                            code != HttpStatusCode.BadRequest;
                    }

                    // The Error Response is null which is indicative of either
                    // a bad request or some other problem
                    return false;
                }
            }
        }
#endif