anchor.diff:  
   -spec stop_workers([pid()]) -> 'ok'.
   stop_workers(Workers) ->
  -    lists:foreach(fun(Pid) -> Pid ! {stop} end, Workers).
  +    lists:foreach(fun(Pid) -> Pid ! stop end, Workers).
   
   -spec send_states([any_state()], non_neg_integer(), [pid(),...]) ->
   	  non_neg_integer().
  
positive.code:     worker_wait(Env, Opts);
  worker_loop(Load, Env, Opts) ->
      receive
  	{stop} -> exit(normal)
      after
  	0 -> ok
      end,
      receive
  	{stop} ->
  	    exit(normal);
  	{state, State} ->
  	    FilteredState = worker_filter(State, Opts),
  
negative.code: 	    worker_loop(-1, Env, Opts);
  	false ->
  	    receive
  		stop             -> exit(normal);
  		{continue, Load} -> worker_loop(Load, Env, Opts)
  	    end
      end.
  