code: public void locationDidChange (PlaceObject place)
      {
          // unlisten to the old place object if there was one
          if (_place != null) {
              _place.removeListener(this);
          }
  
          // listen to the new one
          _place = place;
          if (_place != null) {
              _place.addListener(this);
          }
      }
docs: inherit documentation