anchor.diff:      S1#state{prev_extra=0,
                planned_trims=tl(S#state.planned_trims)}.
   
  +stop_pre(S) ->
  +    S#state.pid /= undefined.
  +
  +stop_args(S) ->
  +    [S#state.pid].
  +
  +stop(Pid) ->
  +    catch machi_file_proxy:stop(Pid).
  +
  +stop_post(_, _, _) -> true.
  +
  +stop_next(S, _, _) ->
  +    S#state{pid=undefined, prev_extra=0}.
  +
   %% Property
   
   prop_ok() ->
  -  cleanup(),
  -  ?FORALL({I, T},
  -          {shuffle_interval(), shuffle_interval()},
  -    ?FORALL(Cmds, parallel_commands(?MODULE, initial_state(I, T)),
  -    begin
  -        {H, S, Res} = run_parallel_commands(?MODULE, Cmds),
  -        %% case S#state.pid of
  -        %%     undefined -> noop;
  -        %%     Pid ->
  -        %%         machi_file_proxy:stop(Pid)
  -        %% end,
  -        pretty_commands(?MODULE, Cmds, {H, S, Res},
  -                        aggregate(command_names(Cmds), Res == ok))
  -    end)
  -  ).
  +    cleanup(),
  +    ?FORALL({I, T},
  +            {shuffle_interval(), shuffle_interval()},
  +            ?FORALL(Cmds, parallel_commands(?MODULE, initial_state(I, T)),
  +                    begin
  +                        {H, S, Res} = run_parallel_commands(?MODULE, Cmds),
  +                        cleanup(),
  +                        pretty_commands(?MODULE, Cmds, {H, S, Res},
  +                                        aggregate(command_names(Cmds), Res == ok))
  +                    end)).
   
   %% Test for tester functions
   chopper_test_() ->
  
positive.code: -define(QC_OUT(P),
          eqc:on_output(fun(Str, Args) -> io:format(user, Str, Args) end, P)).
  
  
  %% EUNIT TEST DEFINITION
  eqc_test_() ->
  
negative.code: 
  write_next(S, Res, [_Pid, Offset, {Bin, _Tag, _Csum}]) ->
      S0 = case is_ok(Res) of
          true ->
              S#state{written = lists:sort(S#state.written ++ [{Offset, iolist_size(Bin)}]) };
          _ ->
              S
      end,
      S0#state{prev_extra = 0, planned_writes=tl(S0#state.planned_writes)}.
  
  
  write(Pid, Offset, {Bin, Tag, Csum}) ->
      Meta = [{client_csum_tag, Tag},
  