anchor.diff:  
   -define(NUM_TESTS, 200).
   
  +-define(ETS, derflow_ets_eqc).
  +
   -define(QC_OUT(P),
           eqc:on_output(fun(Str, Args) -> io:format(user, Str, Args) end, P)).
   
   derflow_ets_test_() ->
       {timeout, 60,
        ?_assert(eqc:quickcheck(
  -                eqc:numtests(?NUM_TESTS, ?QC_OUT(?MODULE:prop_statem()))))}.
  +                eqc:numtests(?NUM_TESTS,
  +                             ?QC_OUT(?MODULE:prop_sequential())))),
  +    ?_assert(eqc:quickcheck(
  +               eqc:numtests(?NUM_TESTS,
  +                            ?QC_OUT(?MODULE:prop_parallel()))))
  +    }.
   
   %% Generators
   declare(Type, Ets) ->
  
positive.code: postcondition(_S,{call,_,_,_},_Res) ->
      true.
  
  %% Property for the state machine.
  prop_statem() ->
      ?FORALL(Cmds, commands(?MODULE),
              begin
                  {H, S, Res} = run_commands(?MODULE, Cmds),
                  ?WHENFAIL(
                      io:format("History: ~p~nState: ~p~nRes: ~p~n", [H, S, Res]),
                      Res == ok)
              end).
  
  -endif.
  -endif.
  
negative.code: next_state(S,_V,{call,_,_,_}) ->
      S.
  
  precondition(#state{store=Store},
               {call, ?MODULE, read, [Id, _Threshold, _Store]}) ->
      case dict:find(Id, Store) of
          error ->
              %% Not declared.
  