code: public static Predicate<ReactiveSensorEvent> filterSensorChanged() {
      return new Predicate<ReactiveSensorEvent>() {
        @Override public boolean test(ReactiveSensorEvent event) throws Exception {
          return event.isSensorChanged();
        }
      };
    }
docs: Predicate, which can be used in filter(...) method from RxJava
  to filter all events in which sensor value has changed
  
  @return BiPredicate<ReactiveSensorEvent, Boolean> predicate indicating if sensor value has
  changed