anchor.diff:  %% cleaning up. When it returns, the gen_server terminates with Reason.
   %% The return value is ignored.
   %%--------------------------------------------------------------------
  +-spec terminate(any(), #state{}) -> ok.
   terminate(_Reason, _State) ->
       ok.
   
  
positive.code: %%                         {stop, Reason}
  %% Description: Initiates the server
  %%--------------------------------------------------------------------
  init([]) ->
      {ok, #state{start=erlang:now(), map=gb_trees:empty()}}.
  
  
negative.code: %% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}
  %% Description: Convert process state when code is changed
  %%--------------------------------------------------------------------
  -spec code_change(any(), #state{}, any()) -> {ok, #state{}}.
  code_change(_OldVsn, State, _Extra) ->
      {ok, State}.
  
  