/// <summary>
 /// Function to download HTML web page
 /// </summary>
 /// <param name="_URL">URL address to download web page</param>
 /// <returns>HTML contents as a string</returns>
 public static string DownloadHTMLPage(string _URL, string _accessToken)
 {
     var fb = new FacebookClient(_accessToken);
     return fb.GetPage(_URL);
 }