anchor.diff:  
   init([]) ->
       process_flag(trap_exit, true),
  -    {ok, gb_trees:empty()}.
  +    {ok, maps:new()}.
   
   -spec handle_call(term(), term(), state()) ->
           {'noreply', state()} |
  
positive.code: 
  %%------------------------------------------------------------------------
  
  -type state() :: gb_trees:tree(pid(), {pid(), reference()}).
  
  %%------------------------------------------------------------------------
  
  
negative.code: -spec handle_info(term(), state()) -> {'noreply', state()}.
  
  handle_info({'DOWN', _, process, Caller, normal}, S) ->
      {noreply, maps:remove(Caller, S)};
  handle_info({'DOWN', _, process, Caller, Reason}, S) ->
      case maps:get(Caller, S, undefined) of
  	undefined ->
  	    {noreply, S};
  	{_, _} = To ->
  	    gen_server:reply(To, {badrpc, {'EXIT', Reason}}),
  	    {noreply, maps:remove(Caller, S)}
      end;
  handle_info({From, {sbcast, Name, Msg}}, S) ->
      _ = case catch Name ! Msg of  %% use catch to get the printout
  