void service_GetWorldNewsCompleted(object sender, GetWorldNewsCompletedEventArgs e)
        {
            AsyncManager.OutstandingOperations.Decrement();
            var localResult = e.Result;

            if (!AsyncManager.Parameters.ContainsKey("result"))
            {
                AsyncManager.Parameters["result"] = localResult.Convert();
            }
            else
            {
                var result = AsyncManager.Parameters["result"] as IEnumerable <NewsModel>;
                AsyncManager.Parameters["result"] = result.Union(localResult.Convert());
            }
        }
        void service_GetWorldNewsCompleted(object sender, GetWorldNewsCompletedEventArgs e)
        {
            AsyncManager.OutstandingOperations.Decrement();
            var localResult = e.Result;

            if (!AsyncManager.Parameters.ContainsKey("result"))
            {
                AsyncManager.Parameters["result"] = localResult.Convert();
            }
            else
            {
                var result = AsyncManager.Parameters["result"] as IEnumerable<NewsModel>;
                AsyncManager.Parameters["result"] = result.Union(localResult.Convert());
            }
        }