# Buggy code
def unwrap_actor_handle(worker, wrapper):
    """Make an ActorHandle from the stored fields.

    Args:
        worker: The worker that is unwrapping the actor handle.
        wrapper: An ActorHandleWrapper instance to unwrap.

    Returns:
        The unwrapped ActorHandle instance.
    """
    driver_id = worker.task_driver_id.id()
    register_actor_signatures(
        worker,
        driver_id,
        wrapper.class_name,
        wrapper.actor_method_names,
        wrapper.actor_method_num_return_vals,
    )

    actor_handle_class = make_actor_handle_class(wrapper.class_name)
    actor_object = actor_handle_class.__new__(actor_handle_class)
    actor_object._manual_init(
        wrapper.actor_id,
        wrapper.actor_handle_id,
        wrapper.actor_cursor,
        wrapper.actor_counter,
        wrapper.actor_method_names,
        wrapper.actor_method_num_return_vals,
        wrapper.method_signatures,
        wrapper.checkpoint_interval,
    )
    return actor_object


# Traceback (ImportError)
Traceback (most recent call last):
File "/home/ubuntu/ray/python/ray/worker.py", line 1694, in fetch_and_execute_function_to_run
function = pickle.loads(serialized_function)
File "/home/ubuntu/ray/python/ray/tune/registry.py", line 12, in <module>
from ray.tune.trainable import Trainable, wrap_function
File "/home/ubuntu/ray/python/ray/tune/__init__.py", line 6, in <module>
from ray.tune.tune import run_experiments
File "/home/ubuntu/ray/python/ray/tune/tune.py", line 8, in <module>
from ray.tune.hyperband import HyperBandScheduler
File "/home/ubuntu/ray/python/ray/tune/hyperband.py", line 8, in <module>
from ray.tune.trial_scheduler import FIFOScheduler, TrialScheduler
File "/home/ubuntu/ray/python/ray/tune/trial_scheduler.py", line 5, in <module>
from ray.tune.trial import Trial
File "/home/ubuntu/ray/python/ray/tune/trial.py", line 15, in <module>
from ray.tune.registry import _default_registry, get_registry, TRAINABLE_CLASS
ImportError: cannot import name '_default_registry'

# Fixed code
def unwrap_actor_handle(worker, wrapper):
    """Make an ActorHandle from the stored fields.

    Args:
        worker: The worker that is unwrapping the actor handle.
        wrapper: An ActorHandleWrapper instance to unwrap.

    Returns:
        The unwrapped ActorHandle instance.
    """
    driver_id = worker.task_driver_id.id()
    register_actor_signatures(
        worker,
        driver_id,
        wrapper.class_id,
        wrapper.class_name,
        wrapper.actor_method_names,
        wrapper.actor_method_num_return_vals,
        wrapper.actor_creation_resources,
        wrapper.actor_method_cpus,
    )

    actor_handle_class = make_actor_handle_class(wrapper.class_name)
    actor_object = actor_handle_class.__new__(actor_handle_class)
    actor_object._manual_init(
        wrapper.actor_id,
        wrapper.class_id,
        wrapper.actor_handle_id,
        wrapper.actor_cursor,
        wrapper.actor_counter,
        wrapper.actor_method_names,
        wrapper.actor_method_num_return_vals,
        wrapper.method_signatures,
        wrapper.checkpoint_interval,
        wrapper.actor_creation_dummy_object_id,
        wrapper.actor_creation_resources,
        wrapper.actor_method_cpus,
    )
    return actor_object