return Observable.create(emitter -> {
            FirebaseAuth auth = FirebaseAuth.getInstance();
            auth.signInAnonymously()
                    .addOnCompleteListener(task -> {
                        if (task.isSuccessful()) {
                            emitter.onNext(true);
                            emitter.onComplete();
                        } else {
                            emitter.onError(task.getException());
                        }
                    });

        });