Atari parameters with world model as policy.

def ppo_original_world_model():
  """Atari parameters with world model as policy."""
  hparams = ppo_original_params()
  hparams.policy_network = "next_frame_basic_deterministic"
  hparams_keys = hparams.values().keys()
  video_hparams = basic_deterministic_params.next_frame_basic_deterministic()
  for (name, value) in six.iteritems(video_hparams.values()):
    if name in hparams_keys:
      hparams.set_hparam(name, value)
    else:
      hparams.add_hparam(name, value)
  # Mostly to avoid decaying WM params when training the policy.
  hparams.weight_decay = 0
  return hparams