public static string DetermineUriForRequest(string appID, string redirectUrl, bool isRedirectUrlEncoded = false, 
            ExtendedPermissions permissions = ExtendedPermissions.None, AuthorizationPromptStyle promptType = AuthorizationPromptStyle.Popup)
        {
            if (!isRedirectUrlEncoded)
                redirectUrl = redirectUrl.UrlEncode();

            string url = string.Format(CultureInfo.CurrentUICulture, URL_ACCESS_TOKEN_REQUEST_FMT, appID, redirectUrl, permissions.Print(), promptType.Print());
            return url;
        }