code: def _failure(self, task, exception):
      failure = {
          "task": self._task_to_str(task),
          "exception": str(exception),
      }
      self._failure_events.append(failure)
  
file_path: gokart/gokart/slack/event_aggregator.py
imports: import os
  from logging import getLogger
  from typing import List, TypedDict
  import luigi
label_desc: Use image node_id 6 for calling the EventAggregator obj's underlying member method code with example usage: obj._failure(task, exception) without return types