anchor.diff:  -ifdef(EQC).
   -include_lib("eqc/include/eqc.hrl").
   -include_lib("eqc/include/eqc_statem.hrl").
  +-define(QC_OUT(P),
  +        eqc:on_output(fun(Str, Args) -> io:format(user, Str, Args) end, P)).
   
   -include_lib("eunit/include/eunit.hrl").
   
   hashtree_test_() ->
       {timeout, 30,
           fun() ->
  -                ?assert(eqc:quickcheck(eqc:testing_time(29,
  -                            hashtree_eqc:prop_correct())))
  +                ?assert(eqc:quickcheck(?QC_OUT(eqc:testing_time(29,
  +                            hashtree_eqc:prop_correct()))))
           end
       }.
   
  
positive.code:                                             ?assertEqual(lists:usort(Expected),
                                                  lists:usort(KeyDiff)),
  
                                              hashtree:destroy(T1),
                                              hashtree:destroy(T2),
                                              true
                                      end
                              end
  
negative.code:                             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),
  