code: def test_default_policy():
      """unit tests"""
      default_policy = DefaultPolicy(
          {
              "policy_0": DummyFlatPolicy("action_0"),
              "policy_1": DummyFlatPolicy("action_1"),
          }
      )
      action = default_policy.compute_action(
          observation={},
          actor_id=ActorID("policy_0", 0),
          deterministic=True,
      )
      assert "action_0" in action
      action = default_policy.compute_action(
          observation={},
          actor_id=ActorID("policy_1", 0),
          deterministic=True,
      )
      assert "action_1" in action
  
      default_policy = DefaultPolicy(
          {"policy_0": DummyFlatPolicy("action_0")}
      )
      action = default_policy.compute_action(
          observation={}, actor_id=None, deterministic=True
      )
      assert "action_0" in action
  
file_path: maze/maze/test/core/agent/test_default_policy.py
imports: from typing import Tuple, Sequence, Optional
  import numpy
  from maze.core.agent.default_policy import DefaultPolicy
  from maze.core.agent.flat_policy import FlatPolicy
  from maze.core.env.action_conversion import ActionType
  from maze.core.env.observation_conversion import ObservationType
  from maze.core.env.structured_env import ActorID
label_desc: Use image node_id 1 for calling a global function with example usage: test_default_policy() without return types