title: make download resumable using c#
body: <p>I am using this method (<code>WebClient</code> Class) for downloading a file from the Internet :</p>
  
  <pre><code>private Task DownloadUpdate(string url, string fileName)
  {
         var wc = new WebClient();
         return wc.DownloadFileTaskAsync(new Uri(url), @"c:\download" + fileName);
  }
  </code></pre>
  
  <p>How can I make the download <em>resumable</em> using the above code?  </p>