public Observable<Tuple2<String, Integer>> wordCount1(Observable<String> words) {
    	return words.groupBy(e -> e).flatMap(e -> e.count().toObservable().map(x -> Tuples.of(e.getKey(), x.intValue())));
    }

    public Single<Map<String, Integer>> wordCount2(Observable<String> words) {
        return words.reduce(new HashMap<String, Integer>(), (a, b) -> {
            if (a.containsKey(b)) { a.put(b, a.get(b) + 1); } else { a.put(b, 1); }
            return a;
        });
    }