anchor.diff:      {ok, #state{port = Port}}.
   
   % @private
  -handle_call(get_value, _From, #state{last_val=Val}=State) -> 
  +handle_call(get_value, _From, #state{last_val = Val} = State) ->
       {reply, Val, State}.
   
   % @private
   handle_cast(Request, _State) -> error({unknown_cast, Request}).
   
   % @private
  -handle_info({Port,{data,Data}}, #state{port=Port}=State) -> 
  +handle_info({Port, {data, Data}}, #state{port = Port} = State) ->
       case Data of
  -	<<_, _, D1, D2, D3, 10>> when $0 =< D1, D1 =< $9,
  -				      $0 =< D2, D2 =< $9,
  -				      $0 =< D3, D3 =< $9 ->
  -	    Val = (D1-$0)*100+(D2-$0)*10+(D3-$0),
  -	    {noreply, State#state{last_val=Val}};
  -	_ ->
  -	    {noreply, State}
  +        <<_, _, D1, D2, D3, 10>> when $0 =< D1, D1 =< $9,
  +                                      $0 =< D2, D2 =< $9,
  +                                      $0 =< D3, D3 =< $9 ->
  +            Val = (D1 - $0) * 100 + (D2 - $0) * 10 + (D3 - $0),
  +            {noreply, State#state{last_val = Val}};
  +        _ ->
  +            {noreply, State}
       end.
  -	    
  -    
  +
  +
   
   % @private
   code_change(_OldVsn, State, _Extra) -> {ok, State}.
   
   % @private
   terminate(_Reason, _State) -> ok.
  -
  -%--- Internal ------------------------------------------------------------------
  -
  
positive.code: -behavior(gen_server).
  
  % API
  -export([start_link/1, get/0]).
  
  % Callbacks
  -export([init/1]).
  
negative.code: %--- API -----------------------------------------------------------------------
  
  % @private
  start_link(Slot, _Opts) ->
      gen_server:start_link({local, ?MODULE}, ?MODULE, Slot, []).
  
  get() ->
  