docs: function WMURLShortener_shorten(longUrl,    // @arg URLString
                                  callback) { // @arg Function - callback(err:Error|null, str:String):void
                                              // @ret void
  //{@dev
      $args(WMURLShortener_shorten, arguments);
  //}@dev
      var that = this;
      var xhr = new XHRProxy();
      var retry = WMURLShortener_shorten["bind"](that, longUrl, callback);
      xhr["on"]("load", _createListener(that, xhr, retry, function(err){
          if(!!err) return callback(err, "");
          callback(null, xhr["response"]["id"]);
      }));
      xhr["open"]('POST', 'https://www.googleapis.com/urlshortener/v1/url', true);
      xhr["setRequestHeader"]('Content-Type', 'application/json');
      xhr["responseType"] = "json";
      xhr["send"](JSON["stringify"]({'longUrl': longUrl}));
  }