@Override public void acceptOffer(Offer offer){
  futureAcceptedOffers.onNext(offer);
  offers.remove(offer);
  acceptedOffers.add(offer);
}

@ Override public void acceptOffer ( Offer offer ) { futureAcceptedOffers . onNext ( offer ) ; offers . remove ( offer ) ; acceptedOffers . add ( offer ) ; }
accept offer remove from offers list update corresponding app usage
