anchor.diff:                                        {add, #ad{id=Id, counter=CounterId}},
                                         undefined)
   
  -                end, lists:sublist(Ids, 6, 10)),
  +                end, TriforkAdIds),
   
       %% Union ads.
       {ok, Ads} = lasp:declare(?SET),
  
positive.code:     %% advertisements.
  
      %% Generate a series of unique identifiers.
      Ids = lists:map(fun(_) -> druuid:v4() end, lists:seq(1, 10)),
      lager:info("Identifiers are: ~p", [Ids]),
  
      %% Generate Rovio's advertisements.
      {ok, RovioAds} = lasp:declare(?SET),
  
negative.code:                                       {add, #ad{id=Id, counter=CounterId}},
                                        undefined)
  
                  end, RovioAdIds),
  
      %% Generate Trifork's advertisements.
      {ok, TriforkAds} = lasp:declare(?SET),
  