code: def attention_mask_ignore_padding(inputs, dtype=tf.float32):
    
    inputs = rename_length_to_memory_length(inputs)
    return mtf.cast(mtf.equal(inputs, 0), dtype) * -1e9
docs: Bias for encoder-decoder attention.
  
    Args:
      inputs: a mtf.Tensor with shape [..., length_dim]
      dtype: a tf.dtype
  
    Returns:
      a mtf.Tensor with shape [..., memory_length_dim]