Tiny set of hparams for model-free PPO.

def rlmf_tiny():
  """Tiny set of hparams for model-free PPO."""
  hparams = rlmf_original()
  hparams = hparams.override_from_dict(rlmf_tiny_overrides())
  hparams.batch_size = 2
  hparams.base_algo_params = "ppo_original_tiny"
  hparams.add_hparam("ppo_epochs_num", 3)
  hparams.add_hparam("ppo_epoch_length", 2)
  return hparams