anchor.diff:          width,
           mem_levels
       }).
  -
  -
  -initial_state() ->
  -    #state{
  -        only1 = [],
  -        only2 = [],
  -        both = []
  -    }.
   
   integer_to_binary(Int) ->
       list_to_binary(integer_to_list(Int)).
  
positive.code:                                             true
                                      end
                              end
                                  )
                          end)))).
  
  -endif.
  
negative.code: 
  
  prop_correct() ->
      ?FORALL({Segments, Width, MemLevels}, {oneof(?POWERS), oneof(?POWERS), 4},
      ?FORALL(Cmds,commands(?MODULE, #state{segments=Segments*Segments, width=Width,
                  mem_levels=MemLevels, only1=[], only2=[], both=[]}),
          ?TRAPEXIT(
              aggregate(command_names(Cmds),
                  begin
                      {_H,S,Res} = HSR = run_commands(?MODULE,Cmds),
                      pretty_commands(?MODULE, Cmds, HSR,
                                      ?WHENFAIL(
                                         begin
                                             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,
  