anchor.diff:  
   init([]) ->
       gen_server:cast(self(), start_watts),
  -    {ok, #state{}}.
  +    {ok, #state{start = erlang:system_time(seconds)}}.
   
   handle_call(_Request, _From, State) ->
       {reply, ignored, State}.
  
positive.code:     start_web_interface(),
      stop(),
      {noreply, State};
  handle_cast(stop, State) ->
      {stop, normal, State};
  handle_cast(_Msg, State) ->
      {noreply, State}.
  
negative.code: -export([code_change/3]).
  
  -record(state, {
            start = undefined
           }).
  
  %% API.
  