anchor.diff:              ?LET({Object, Update},
                    {Type:new(), Type:gen_op()},
                     begin
  -                    {ok, X} = Type:update(Update, undefined, Object),
  -                    X
  +                    case Type:update(Update, undefined, Object) of
  +                        {ok, X} ->
  +                            X;
  +                        _ ->
  +                            Object
  +                    end
                     end)
       end.
   
  
positive.code:             ?LET({Object, Update},
                   {Type:new(), Type:gen_op()},
                    begin
                      {ok, X} = Type:update(Update, undefined, Object),
                      X
                    end)
      end.
  
  
negative.code: 
  -define(SECS, 60).
  -define(NUM_TESTS, 200).
  -define(LATTICES, [lasp_ivar,
                     riak_dt_gset,
                     riak_dt_orset,
                     riak_dt_gcounter]).
  
  -define(ETS, lasp_ets_eqc).
  
  -define(QC_OUT(P),
          eqc:on_output(fun(Str, Args) ->
                  io:format(user, Str, Args)
          end, P)).
  
  lasp_ets_sequential_test_() ->
      {timeout, 60,
  