class_docstr: Instance storage stores the states of instances in the storage. It also
  allows users to subscribe to instance status changes to trigger reconciliation
  with cloud provider.
code: def add_status_change_subscribers(
      self, subscribers: List[InstanceUpdatedSubscriber]
  ):
      self._status_change_subscribers.extend(subscribers)
  
file_path: ray/python/ray/autoscaler/v2/instance_manager/instance_storage.py
imports: import copy
  import logging
  from abc import ABCMeta, abstractmethod
  from typing import Dict, List, Optional, Set, Tuple
  from ray.autoscaler.v2.instance_manager.storage import Storage, StoreStatus
  from ray.core.generated.instance_manager_pb2 import Instance, InstanceUpdateEvent
label_desc: Use image node_id 2 for calling the InstanceStorage obj's underlying member method code with example usage: obj.add_status_change_subscribers(subscribers) without return types