code: def _add_ready_worker(
      self, pool: _ActorPool
  ) -> ray.actor.ActorHandle:
      actor = PoolWorker.remote()
      ready_ref = actor.get_location.remote()
      pool.add_pending_actor(actor, ready_ref)
      # Wait until actor has started.
      ray.get(ready_ref)
      # Mark actor as running.
      has_actor = pool.pending_to_running(ready_ref)
      assert has_actor
      return actor
  
imports: import collections
  import time
  import pytest
  import ray
  from ray.data._internal.compute import ActorPoolStrategy
  from ray.data._internal.execution.operators.actor_pool_map_operator import AutoscalingConfig, AutoscalingPolicy, _ActorPool
  from ray.data._internal.execution.util import make_ref_bundles
  from ray.tests.conftest import *
label_desc: Use image node_id 1 for calling the TestActorPool obj's underlying member method code with example usage: obj._add_ready_worker(pool) and returns: actor