function loadImagesRecursivelly(urls:Array<String>):Future<Array<Image>> {
        var url:String = urls[0];
        if (url != null) {
            return checkImage(url).recover(function(error:Error){
                var mockImage:Image = new Image();
                mockImage.src = "http://iservs-mbp.fritz.box:8000/placeholder.png";
                return Future.sync(mockImage);
            }).map(function(image:Image){
                playground.appendChild(image);
                return image;
            }).flatMap(function(image:Image) {
                return
                    loadImagesRecursivelly(urls.slice(1))
                    .map(function (results) {
                        return [image].concat(results);
                    });
            });
        } else {
            return Future.sync([]);
        }
    }