anchor.diff:  
   register_object(Service, Path, Object) ->
       gen_server:call(Service, {register_object, Path, Object}).
  +
  +unregister_object(Service, Object) ->
  +    gen_server:call(Service, {unregister_object, Object}).
   
   %%
   %% gen_server callbacks
  
positive.code: 
  terminate(_Reason, _State) ->
      terminated.
  
negative.code: 	    true = link(Object),
  	    Objects1 = [{Path, Object} | Objects],
  	    {reply, ok, State#state{objects=Objects1}}
      end;
  
  handle_call({unregister_object, Object}, _From, State) ->
      case handle_unregister_object(Object, State) of
  	{ok, State1} ->
  	    {reply, ok, State1};
  	{error, Reason, State1} ->
  	    {reply, Reason, State1};
  	{stop, State1} ->
  	    {stop, normal, State1}
      end;
  
  handle_call(Request, _From, State) ->
  