anchor.diff:  -include_lib("eqc/include/eqc_statem.hrl").
   -define(QC_OUT(P),
           eqc:on_output(fun(Str, Args) -> io:format(user, Str, Args) end, P)).
  +
  +-define(POWERS, [8, 16, 32, 64, 128, 256, 512, 1024]).
   
   -include_lib("eunit/include/eunit.hrl").
   
  
positive.code: 
  
  prop_correct() ->
      ?FORALL({Segments, Width, MemLevels}, make_treevars(),
      ?FORALL(Cmds,commands(?MODULE, #state{segments=Segments, width=Width,
                  mem_levels=MemLevels}),
          ?TRAPEXIT(
              aggregate(command_names(Cmds), 
                  begin
                          {H,S,Res} = run_commands(?MODULE,Cmds),
                          ?WHENFAIL(
                              begin
                                      io:format("History: ~p\nState: ~p\nRes: ~p\n~p\n",
                                          [H,S,Res, zip(tl(Cmds), [Y || {_, Y} <- H])]),
                                      catch hashtree:destroy(hashtree:close(S#state.tree1)),
                                      catch hashtree:destroy(hashtree:close(S#state.tree2))
                              end,
                              begin
                                      ?assertEqual(ok, Res),
                                      Unique1 = S#state.only1 -- S#state.only2,
  
negative.code:         width,
          mem_levels
      }).
  
  integer_to_binary(Int) ->
      list_to_binary(integer_to_list(Int)).
  