anchor.diff:  -spec handle_info(term(), state()) -> {'noreply', state()}.
   
   handle_info({'DOWN', _, process, Caller, normal}, S) ->
  -    {noreply, gb_trees:delete(Caller, S)};
  +    {noreply, maps:remove(Caller, S)};
   handle_info({'DOWN', _, process, Caller, Reason}, S) ->
  -    case gb_trees:lookup(Caller, S) of
  -        {value, To} ->
  +    case maps:get(Caller, S, undefined) of
  +	undefined ->
  +	    {noreply, S};
  +	{_, _} = To ->
   	    gen_server:reply(To, {badrpc, {'EXIT', Reason}}),
  -	    {noreply, gb_trees:delete(Caller, S)};
  -	none ->
  -	    {noreply, S}
  +	    {noreply, maps:remove(Caller, S)}
       end;
   handle_info({From, {sbcast, Name, Msg}}, S) ->
       _ = case catch Name ! Msg of  %% use catch to get the printout
  
positive.code: 
  %%------------------------------------------------------------------------
  
  -type state() :: gb_trees:tree(pid(), {pid(), reference()}).
  
  %%------------------------------------------------------------------------
  
  
negative.code: 		      end,
  		  gen_server:reply(To, Reply)
  	  end),
      {noreply, maps:put(Caller, To, S)}.
  
  
  %% RPC aid functions ....
  