old_contents: from ics_demo.handlers import BaseHandler
  from ics_demo.handlers import DemoBaseHandler, DemoRabbitHandler, DemoCarrotHandler, DemoCorpsHandler
  
  uuid_regex = "([0-9a-z]{8}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{12})"
  
  urls = [
      (r"/", BaseHandler),
      (r"/demo", DemoBaseHandler),
      (r"/demo/rabbit", DemoRabbitHandler),
      (r"/demo/rabbit/" + uuid_regex, DemoRabbitHandler),
      (r"/demo/carrot", DemoCarrotHandler),
      (r"/demo/carrot/" + uuid_regex, DemoCarrotHandler),
      (r"/demo/corps", DemoCorpsHandler),
      (r"/demo/corps/" + uuid_regex, DemoCorpsHandler),
  
  ]
  
new_contents: from ics_demo.handlers import BaseHandler
  from ics_demo.handlers import DemoBaseHandler, DemoRabbitHandler, DemoCarrotHandler, DemoCorpsHandler
  
  uuid_regex = "([0-9a-z]{8}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{12})"
  
  urls = [
      (r"/", BaseHandler),
      (r"/demo", DemoBaseHandler),
      (r"/demo/rabbit", DemoRabbitHandler),
      (r"/demo/rabbit/%s" % uuid_regex, DemoRabbitHandler),
      (r"/demo/carrot", DemoCarrotHandler),
      (r"/demo/carrot/%s" % uuid_regex, DemoCarrotHandler),
      (r"/demo/corps", DemoCorpsHandler),
      (r"/demo/corps/%s" % uuid_regex, DemoCorpsHandler),
  
  ]
  
subject: change + to % in routes.py