anchor.diff:  %% completed.
   %%
   set_next_rebuild(T) ->
  -    put(T, hashtree:set_next_rebuild(get(T), incremental)).
  -
  +    put(T, hashtree:set_next_rebuild(get(T), incremental)),
  +    ok.
   
   %% Wrap hashtree:insert to (over)write key with a new hash to a single
   %% table and insert into the model tree.
  
positive.code:          {trunc(math:pow(Width, Levels)), Width, MemLevels}).
  
  mark() ->
      frequency([{1, mark_empty}, {5, mark_open}]).
  
  %% Generate tree ids - the first one is used for the test, the others are added
  %% as empty hashtrees.
  
negative.code:     end;
  %% After a comparison, check against the results against
  %% the ETS table containing the *snapshot* copies.
  postcondition(_S,{call, _, local_compare, _},  Result0) ->
      Result = lists:sort(Result0),
      T1Top = hashtree:top_hash(get(t1)),
      T2Top = hashtree:top_hash(get(t2)),
      Expect = expect_compare(),
      case Expect of
          [] ->
              eqc_statem:conj([eq({result, Expect}, {result, Result}),
                               eq({top, T1Top}, {top, T2Top})]);
          _ ->
              eq(Expect, Result)
      end;
  postcondition(_S,{call,_,_,_},_R) ->
      true.
  
  