class_docstr: Encapsulates one or more policies identified by policy IDs.
  
  :param policies: Dict of policy IDs and corresponding policies.
class_docstr_tok: ["Encapsulates","one","or","more","policies","identified","by","policy","IDs",".",":","param","policies",":","Dict","of","policy","IDs","and","corresponding","policies","."]
docstr: Return policy corresponding to the given actor ID (or the single available policy if no actor ID is provided)
  
  :param actor_id: Actor ID to get policy for
  :return: Flat policy corresponding to the actor ID
docstr_tok: ["Return","policy","corresponding","to","the","given","actor","ID","(","or","the","single","available","policy","if","no","actor","ID","is","provided",")",":","param","actor_id",":","Actor","ID","to","get","policy","for",":","return",":","Flat","policy","corresponding","to","the","actor","ID"]
code: def policy_for(self, actor_id: Optional[ActorID]) -> FlatPolicy:
      """Return policy corresponding to the given actor ID (or the single available policy if no actor ID is provided)
  
      :param actor_id: Actor ID to get policy for
      :return: Flat policy corresponding to the actor ID
      """
      if actor_id is None:
          assert (
              len(self.policies.items()) == 1
          ), "no policy ID provided but multiple policies are available"
          return list(self.policies.values())[0]
      else:
          return self.policies[actor_id.step_key]
  
file_path: maze/maze/core/agent/default_policy.py
imports: from typing import Tuple, Sequence, Optional
  from maze.core.agent.flat_policy import FlatPolicy
  from maze.core.agent.policy import Policy
  from maze.core.annotations import override
  from maze.core.env.action_conversion import ActionType
  from maze.core.env.base_env import BaseEnv
  from maze.core.env.maze_state import MazeStateType
  from maze.core.env.observation_conversion import ObservationType
  from maze.core.env.structured_env import ActorID
  from maze.core.utils.factory import Factory, CollectionOfConfigType
label_desc: Use image node_id 5 for calling the DefaultPolicy obj's underlying member method code with example usage: obj.policy_for(actor_id) and returns: list, self