code: def launch(self, port=None):
          
          
          if port is not None:
              self.port = port
          url = 'http://127.0.0.1:{PORT}'.format(PORT=self.port)
          print('Interface starting at {url}'.format(url=url))
          self.listen(self.port)
          # webbrowser.open(url)
          tornado.ioloop.IOLoop.instance().start()
docs: Run the app.