anchor.diff:      {reply, Res, State};
   handle_call({setopts, Opts}, _From, State) ->
       {reply, ok, do_setopts(State, Opts)};
  +handle_call(clean, _From, State) ->
  +    {reply, ok, State#state{tab = treap:empty(), size = 0}};
   handle_call(_Request, _From, State) ->
       Reply = ok,
       {reply, Reply, State}.
  
positive.code: -export([start_link/4, new/2, delete/1, delete/3, lookup/3,
  	 insert/4, info/2, tab2list/1, setopts/2,
  	 dirty_lookup/3, dirty_insert/4, dirty_delete/3,
  	 all/0, test/0]).
  
  %% gen_server callbacks
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  
negative.code: 	Err ->
  	    {error, Err}
      end.
  
  clean(Tab) ->
      lists:foreach(
        fun(Proc) ->
  	      ?GEN_SERVER:call(Proc, clean, ?CALL_TIMEOUT)
        end, get_all_procs(Tab)).
  
  delete(Tab) ->
      lists:foreach(
  