Batch size in examples per TPU core.

    Args:
      model_hparams: model hyperparameters
    Returns:
      an integer

def tpu_batch_size_per_shard(self, model_hparams):
    """Batch size in examples per TPU core.

    Args:
      model_hparams: model hyperparameters
    Returns:
      an integer
    """
    if self.batch_size_means_tokens and not model_hparams.use_fixed_batch_size:
      return model_hparams.batch_size // self.max_length(model_hparams)
    else:
      return model_hparams.batch_size