anchor.diff:                              begin
                                       io:format("History: ~p\nState: ~p\nRes: ~p\n~p\n",
                                           [H,S,Res, zip(tl(Cmds), [Y || {_, Y} <- H])]),
  -                                    catch hashtree:destroy(S#state.tree1),
  -                                    catch hashtree:destroy(S#state.tree2)
  +                                    catch hashtree:destroy(hashtree:close(S#state.tree1)),
  +                                    catch hashtree:destroy(hashtree:close(S#state.tree2))
                               end,
                               begin
                                       ?assertEqual(ok, Res),
  
positive.code: -ifdef(EQC).
  -include_lib("eqc/include/eqc.hrl").
  -include_lib("eqc/include/eqc_statem.hrl").
  
  -include_lib("eunit/include/eunit.hrl").
  
  hashtree_test_() ->
      {timeout, 30,
          fun() ->
                  ?assert(eqc:quickcheck(eqc:testing_time(29,
                              hashtree_eqc:prop_correct())))
          end
      }.
  
  
negative.code:                                             ?assertEqual(lists:usort(Expected),
                                                  lists:usort(KeyDiff)),
  
                                              catch hashtree:destroy(hashtree:close(T1)),
                                              catch hashtree:destroy(hashtree:close(T2)),
                                              true
                                      end
                              end
  