Facebook.FacebookOAuthClient.ExchangeCodeForAccessToken C# (CSharp) Method

        public object ExchangeCodeForAccessToken(string code)
        {
            return ExchangeCodeForAccessToken(code, null);
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            var url = HttpContext.Current.Request.Url;
            FacebookOAuthResult oauthResult;

            var oauthClient = new FacebookOAuthClient { AppId = AppId, AppSecret = AppSecret, RedirectUri = new Uri(_silverlightFacebookCallback) };

            if (oauthClient.TryParseResult(url, out oauthResult))
            {
                if (oauthResult.IsSuccess)
                {
                    var result = (IDictionary<string, object>)oauthClient.ExchangeCodeForAccessToken(oauthResult.Code);
                    AccessToken = result["access_token"].ToString();
                    Label1.Text = AccessToken;
                }
                else
                {
                    ErrorDescription = oauthResult.ErrorDescription;
                }

                Response.Cache.SetCacheability(HttpCacheability.NoCache);
            }
            else
            {
                Response.Redirect("~/");
            }
        }