code: public Evaluator sync(Map<String, List<Subscription>> subs) {
      Set<String> removed = subscriptions.keySet();
      removed.removeAll(subs.keySet());
      removed.forEach(this::removeGroupSubscriptions);
      subs.forEach(this::addGroupSubscriptions);
      return this;
    }
docs: Synchronize the internal set of subscriptions with the map that is passed in.
  
  @param subs
  Complete set of subscriptions for all groups. The keys for the map are the
  group names.
  @return
  This instance for chaining of update operations.