@NonNull
    private static ObservableTransformer<Boolean, Boolean> onSubscribeSetText(Button button, @StringRes int textResId) {
        return booleanObservable -> booleanObservable
                .doOnSubscribe((disposable) -> button.setText(textResId))
                .subscribeOn(AndroidSchedulers.mainThread());
    }
Function that returns a {@link io.reactivex.ObservableTransformer} which will on subscribe
set a text on a button using a proper thread

@param button the button to set text on
@param textResId the text resource id
@return the transformer
sample/src/main/java/com/polidea/rxandroidble2/sample/example4_characteristic/advanced/AdvancedCharacteristicOperationExampleActivity.java