HParams for training languagemodel_lm1b8k on tpu.  92M Params.

def transformer_lm_tpu_0():
  """HParams for training languagemodel_lm1b8k on tpu.  92M Params."""
  hparams = transformer_clean_big()
  update_hparams_for_tpu(hparams)
  hparams.num_heads = 4  # Heads are expensive on TPUs.
  hparams.batch_size = 4096
  hparams.shared_embedding_and_softmax_weights = False
  hparams.layer_prepostprocess_dropout = 0.1
  return hparams