code: def __init__(self):
      self.events = []
  
file_path: ray/python/ray/autoscaler/v2/tests/test_instance_storage.py
imports: import copy
  import os
  import sys
  from unittest import mock
  import pytest
  from ray.autoscaler.v2.instance_manager.instance_storage import InstanceStorage, InstanceUpdatedSubscriber, InstanceUpdateEvent
  from ray.autoscaler.v2.instance_manager.storage import InMemoryStorage
  from ray.core.generated.instance_manager_pb2 import Instance
label_desc: Use image node_id 1 to create a new DummySubscriber object from inherited base classes: InstanceUpdatedSubscriber with example: obj = DummySubscriber()