docstr: Returns the number of Policy actors in this shard.
docstr_tok: ["Returns","the","number","of","Policy","actors","in","this","shard","."]
code: def __len__(self):
      """Returns the number of Policy actors in this shard."""
      return len(self.policy_actors)
  
imports: import math
  from typing import Any, Dict, List, Optional, Type
  import ray
  from ray.actor import ActorHandle
  from ray.rllib.algorithms.algorithm import Algorithm
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.policy.policy import PolicySpec
  from ray.rllib.utils.actors import create_colocated_actors
  from ray.rllib.utils.tf_utils import get_tf_eager_cls_if_necessary
  from ray.rllib.utils.typing import AlgorithmConfigDict, PolicyID
label_desc: Use image node_id 5 for calling the _Shard obj's underlying member method code with example usage: obj.__len__() and returns: len