old_contents: import webapp2
  
  class Main(webapp2.RequestHandler):
  
      
  
new_contents: import webapp2
  import jinja2
  
  ENV = jinja2.Environment()
  
  
  
  class MainHandler(webapp2.RequestHandler):
      def get(self):
          
  
  
  
  app = webapp2.
  
      
  
subject: add a bit more code to main.py but need to look up the standard template to get it running