code: def handle_get_request(self, environ, start_response):
          
          connections = [
              s.strip()
              for s in environ.get('HTTP_CONNECTION', '').lower().split(',')]
          transport = environ.get('HTTP_UPGRADE', '').lower()
          if 'upgrade' in connections and transport in self.upgrade_protocols:
              self.server.logger.info('%s: Received request to upgrade to %s',
                                      self.sid, transport)
              return getattr(self, '_upgrade_' + transport)(environ,
                                                            start_response)
          try:
              packets = self.poll()
          except exceptions.QueueEmpty:
              exc = sys.exc_info()
              self.close(wait=False)
              six.reraise(*exc)
          return packets
docs: Handle a long-polling GET request from the client.