private Observable<Boolean> activeState() {
Observable<FragmentEvent> startStopLifecycle =
lifecycle().filter(ev -> ev == FragmentEvent.START || ev == FragmentEvent.STOP);
// now combine with the activeStateSubject and return a new observable with
// the "active state".
Observable<Boolean> combined =
combineLatest(
startStopLifecycle,
activeStateSubject,
(ev, active) -> active && ev == FragmentEvent.START);
return combined.distinctUntilChanged();
}
