MPO: Fix typing that doesn't work in python 3.8.
"""Defines the MPO agent builder, which holds factories for all components."""
import functools
-from typing import Iterator, Optional
+from typing import Iterator, List, Optional
from absl import logging
from acme import core
@@ -205,7 +205,7 @@ class MPOBuilder(builders.ActorLearnerBuilder):
self,
environment_spec: specs.EnvironmentSpec,
policy: actor_core_lib.ActorCore, # Used to get accurate extras_spec.
- ) -> list[reverb.Table]:
+ ) -> List[reverb.Table]:
dummy_actor_state = policy.init(jax.random.PRNGKey(0))
extras_spec = policy.get_extras(dummy_actor_state)
