code: def fetch_events(self, last_id: Optional[str] = None):
      base_uri = "api/v1/async_event/"
      uri = f"{base_uri}?last_id={last_id}" if last_id else base_uri
      return self.client.get(uri)
  
file_path: superset/tests/integration_tests/async_events/api_tests.py
imports: import json
  from typing import Optional
  from unittest import mock
  from superset.extensions import async_query_manager
  from tests.integration_tests.base_tests import SupersetTestCase
  from tests.integration_tests.test_app import app
label_desc: Use image node_id 1 for calling the TestAsyncEventApi obj's underlying member method code with example usage: obj.fetch_events(last_id) and returns: self