old_contents: import tornado.httpserver
  import tornado.ioloop
  import tornado.web
  
  from settings import *
  
  
  class MainHandler(tornado.web.RequestHandler):
      def get(self):
          self.write("Hello, world")
  
  application = tornado.web.Application([
      (r'/', MainHandler),
  ])
  
  if __name__ == "__main__":
      http_server = tornado.httpserver.HTTPServer(application, ssl_options={
          "certfile": PEMFILE,
          "keyfile": KEYFILE
      })
      http_server.listen(443)
      tornado.ioloop.IOLoop.current().start()
  
new_contents: import tornado.httpserver
  import tornado.ioloop
  import tornado.web
  
  from tornado.options import define, options
  
  from settings import *
  
  
  class MainHandler(tornado.web.RequestHandler):
      def get(self):
          self.write("Hello, world")
  
  application = tornado.web.Application([
      (r'/', MainHandler),
  ])
  
  if __name__ == "__main__":
      define("port", default="443", help="Port to listen on")
      define("host", default="localhost", help="Server address to listen on")
      tornado.options.parse_command_line()
      http_server = tornado.httpserver.HTTPServer(application, ssl_options={
          "certfile": PEMFILE,
          "keyfile": KEYFILE
      })
      http_server.listen(int(options.port), address=options.host)
      tornado.ioloop.IOLoop.current().start()
  
subject: Add host, port options.