file_path: garage/tests/garage/tf/policies/test_categorical_gru_policy.py
imports: import pickle
  import numpy
  import pytest
  import tensorflow
  from garage.envs import GymEnv
  from garage.tf.policies import CategoricalGRUPolicy
  from tests.fixtures import TfGraphTestCase
  from tests.fixtures.envs.dummy import DummyBoxEnv, DummyDictEnv, DummyDiscreteEnv
label_desc: Use image node_id 6 for calling the TestCategoricalGRUPolicy obj's underlying member method code with example usage: obj.test_is_pickleable() without return types