在tweetsharp 2.3.1中找不到GetRequesttoken方法

Question

 // instance of twitter
  TwitterService service  = new TwitterService(consumerKey,consumerSecret);   
  service.GetRequestoken((requestToken, response) =>
  {
        if (response.StatusCode == HttpStatusCode.OK)
        {
              Request = requestToken;
              Uri uri = Service.GetAuthorizationUri(requestToken);
              Dispatcher.BeginInvoke(() =>
              {
                     Browser.Navigate(uri);
              });
          }
   });