anchor.diff:  
   -spec add_subscriber(topic(), qos(), subscriber_id()) -> ok.
   add_subscriber(Topic, QoS, SubscriberId) ->
  -    add_subscriber(Topic, QoS, SubscriberId, os:timestamp()).
  -add_subscriber(Topic, QoS, SubscriberId, Timestamp) ->
  -    Key = {SubscriberId, {Topic, QoS, Timestamp}},
  +    Key = {SubscriberId, {Topic, QoS}},
       plumtree_metadata:put(?SUBSCRIBER_DB, Key, node()).
   
   
  
positive.code: 
  subscriptions_for_subscriber_id(SubscriberId) ->
      plumtree_metadata:fold(
        fun({{_, {Topic, QoS, _}}, _}, Acc) ->
                [{Topic, QoS}|Acc]
        end, [], ?SUBSCRIBER_DB,
        [{match, {SubscriberId, '_'}},
  
negative.code:       fun({Key, _}, _) ->
                plumtree_metadata:delete(?SUBSCRIBER_DB, Key)
        end, ok, ?SUBSCRIBER_DB,
        [{match, {SubscriberId, {Topic, '_'}}}]).
  
  -spec remap_subscriptions(subscriber_id()) -> ok.
  remap_subscriptions(SubscriberId) ->
      Node = node(),
      plumtree_metadata:fold(
        fun({{_, {Topic, QoS}}, N}, _) ->
                case N of
                    Node -> ok;
                    _ ->
                        add_subscriber(Topic, QoS, SubscriberId)
                end
        end, ok, ?SUBSCRIBER_DB,
        [{match, {SubscriberId, '_'}},
  