code: def _handle_event(self, sid, namespace, id, data):
          
          namespace = namespace or '/'
          self.logger.info('received event "%s" from %s [%s]', data[0], sid,
                           namespace)
          if self.async_handlers:
              self.start_background_task(self._handle_event_internal, self, sid,
                                         data, namespace, id)
          else:
              self._handle_event_internal(self, sid, data, namespace, id)
docs: Handle an incoming client event.