anchor.diff:                      [Pid]
               end
       end,
  -    {noreply, State#state{ pids = lists:append(Pids, State#state.pids)}};
  +    {noreply, State#state{ pids = sets:union(sets:from_list(Pids), State#state.pids)}};
   
   handle_info({upstream_metadata, At, UpstreamBaseUrl, VersionsFromUpstream}, State) ->
       Unknown = lists:filter(fun({BaseUrl, {{Author, Module}, Version}}) ->
  
positive.code:     {noreply, State#state{ tbd = NewTbd, errors = NewErrors}};
  
  handle_info({'EXIT', Pid, _Reason}, State) ->
      NewPids = case lists:element(Pid, State#state.pids) of
          false -> State#state.pids;
          true ->
              self() ! tick, 
              lists:delete(Pid, State#state.pids)
      end,
      {noreply, State#state{ pids = NewPids }};
  
  
negative.code: 
  -define(TICK_INTERVAL_MILLIS, 10000).
  -define(REFRESH_INTERVAL_MICROS, 60 * 60* 1000* 1000 * 1000).
  -record(state, { pids=sets:new(), retards =[], upstream = dict:new(), tbd = dict:new(), errors = dict:new() }).
  
  -compile(export_all).
  % -----------------------------------------------------------------------------
  