code: def tpu_batch_size_per_shard(self, model_hparams):
      
      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
docs: Batch size in examples per TPU core.
  
      Args:
        model_hparams: model hyperparameters
      Returns:
        an integer