class_docstr: Extend Dask's Worker with routes to handle PubSub machinery
code: def add_subscriber(self, name=None, address=None, **info):
      for pub in self.publishers[name]:
          pub.subscribers[address] = info
  
imports: from __future__ import annotations
  import asyncio
  import logging
  import threading
  import weakref
  from collections import defaultdict, deque
  from dask.utils import parse_timedelta
  from distributed.core import CommClosedError
  from distributed.metrics import time
  from distributed.protocol.serialize import to_serialize
  from distributed.utils import TimeoutError, sync, wait_for
label_desc: Use image node_id 2 for calling the PubSubWorkerExtension obj's underlying member method code with example usage: obj.add_subscriber(name, address) without return types