anchor.diff:  handle_call({identify, Identifier}, _From, State) ->
       lager:info("~p: identifying trace: ~p", [?MODULE, Identifier]),
       {reply, ok, State#state{identifier=Identifier}};
  -handle_call(print, _From, #state{trace=Trace}=State) ->
  +handle_call(print, _From, #state{trace=Trace, file=File}=State) ->
       lager:info("~p: printing trace", [?MODULE]),
   
       lists:foldl(fun({Type, Message}, Count) ->
  
positive.code: -spec init([]) -> {ok, #state{}}.
  init([]) ->
      lager:info("Test orchestrator started on node: ~p", [node()]),
      {ok, #state{trace=[]}}.
  
  %% @private
  -spec handle_call(term(), {pid(), term()}, #state{}) ->
  
negative.code:         Count + 1
      end, 1, Trace),
  
      %% Write trace.
      lists:foreach(fun(Line) ->
          io:format(File, "~p", [Line])
          end, Trace),
  
      {reply, ok, State};
  handle_call(Msg, _From, State) ->
      lager:warning("Unhandled call messages at module ~p: ~p", [?MODULE, Msg]),
  