private void loadAllData(){
        compositeDisposable.add(retrofitInterface

                .getAllCountries()
                .flattenAsObservable((Function<List<Country>, Iterable<?>>) countries -> countries)
                .flatMap( country -> getFlags(new String()))
                .subscribe());

    }
    private Observable<Bitmap> getFlags(String flag) {

        return  retrofitInterface.getFlag(flag)
                .toObservable()
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread());

    }