Set of hyperparameters.

def transformer_ae_a3():
  """Set of hyperparameters."""
  hparams = transformer_ae_base()
  hparams.batch_size = 4096
  hparams.layer_prepostprocess_dropout = 0.3
  hparams.optimizer = "Adafactor"
  hparams.learning_rate = 0.25
  hparams.learning_rate_warmup_steps = 10000
  return hparams