code: def test_pick_ordering_lone_idle(self, ray_start_regular_shared):
      # Test that a lone idle actor is the one that's picked.
      pool = _ActorPool()
      self._add_ready_worker(pool)
      # Ensure that actor has been picked once.
      pool.pick_actor()
      # Add a new, idle actor.
      actor2 = self._add_ready_worker(pool)
      # Check that picked actor is the idle newly added actor.
      picked_actor = pool.pick_actor()
      assert picked_actor == actor2
  
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 7 for calling the TestActorPool obj's underlying member method code with example usage: obj.test_pick_ordering_lone_idle(ray_start_regular_shared) without return types