code: def _get_tpu_strategy(self):
      resolver = tf.distribute.cluster_resolver.TPUClusterResolver("")
      tf.config.experimental_connect_to_cluster(resolver)
      tf.tpu.experimental.initialize_tpu_system(resolver)
      return tf.distribute.experimental.TPUStrategy(resolver)
  
file_path: agents/tf_agents/train/tpu_ppo_learner_test.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl import flags
  from absl import logging
  import tensorflow
  from tf_agents.system import system_multiprocessing
  from tf_agents.train import ppo_learner
  from tf_agents.train import ppo_learner_test_utils
  from tf_agents.utils import test_utils
label_desc: Use image node_id 1 for calling the DistributedPpoLearnerTest obj's underlying member method code with example usage: obj._get_tpu_strategy() and returns: tf