code: public void visit(Paintable paintable, Object group) {
  		if (context.isReady()) {
  			String className = paintable.getClass().getName();
  			if (painters.containsKey(className)) {
  				List<Painter> list = painters.get(className);
  				for (Painter painter : list) {
  					painter.paint(paintable, group, context);
  				}
  			}
  		}
  	}
docs: The visitors visit function.
  
  @param paintable object to draw
  @param group group to draw