anchor.diff:                  {Cache2, NodeQ} = cyclon_cache:pop_oldest_node(Cache1),
                   Subset = cyclon_cache:get_random_subset(shuffle_length() - 1, Cache2),
                   ForSend = cyclon_cache:add_node(Node, 0, Subset),
  -                %io:format("~p",[length(ForSend)]),
                   Pid = pid_groups:get_my(gossip),
                   comm:send_local(Pid, {selected_peer, instance(), {cy_cache, [NodeQ]}}),
                   comm:send_local(Pid, {selected_data, instance(), ForSend}),
  
positive.code: %%      cyclon module.
  -spec select_data(State::state()) -> {ok, state()}.
  select_data({Cache, Node}=State) ->
      ?TRACE_DEBUG("select__data", []),
      NewCache =
          case check_state(State) of
              fail ->
  
negative.code:     {ok, {NewCache, Node}}.
  
  
  %% @doc Process the data from the requestor (P) and select reply data (at Q). <br/>
  %%      Called by the behaviour module upon a p2p_exch message. <br/>
  %%      PData: exchange data from the p2p_exch request <br/>
  %%      Ref: used by the gossip module to identify the request <br/>
  %%      RoundStatus / Round: ignored, as cyclon does not implement round handling
  %%      p2p_exch msg -> seleft_reply_data() is equivalent to cy_subset msg in the
  %%      old cyclon module.
  -spec select_reply_data(PSubset::data(), Ref::pos_integer(), Round::round(),
      State::state()) -> {discard_msg | ok | retry | send_back, state()}.
  select_reply_data(PSubset, Ref, Round, {Cache, Node}) ->
      ?TRACE_DEBUG("select_reply_data", []),
      % this is received at node Q -> integrate results of node P
      QSubset = cyclon_cache:get_random_subset(shuffle_length(), Cache),
      Pid = pid_groups:get_my(gossip),
      comm:send_local(Pid, {selected_reply_data, instance(), {QSubset, PSubset}, Ref, Round}),
      NewCache = cyclon_cache:merge(Cache, Node, PSubset, QSubset, cache_size()),
      {ok, {NewCache, Node}}.
  
  
  %% @doc Integrate the reply data. <br/>
  