CherryPy: URL Routing in App Engine

# main.py
import cherrypy
import wsgiref.handlers


class HelloWorld:
  @cherrypy.expose
  def index(self):
    return "Hello world!"
class GoodDay:
  @cherrypy.expose
  def index(self,num=None):
    reply = "Good Day!"
    if num is not None:
      for x in range(1,int(num)):
        reply += "
Good Day!"
    return (reply)


def main():
  root = HelloWorld()
  root.reply = GoodDay()
  app = cherrypy.tree.mount(root,"/")
  wsgiref.handlers.CGIHandler().run(app)


if __name__ == '__main__':
  main()

Source:
http://appmecha.wordpress.com/2008/10/21/cherrypy-routing-1/