TypeError: sequence_softmax() got an unexpected keyword argument 'x'

[peterzhang2029]

The error occurs when training with machine_translation.py:

Traceback (most recent call last):
  File "machine_translation.py", line 336, in <module>
    train()
  File "machine_translation.py", line 251, in train
    max_length=args.max_length)
  File "machine_translation.py", line 208, in seq_to_seq_net
    decoder_size)
  File "machine_translation.py", line 184, in lstm_decoder_with_attention
    context = simple_attention(encoder_vec, encoder_proj, hidden_mem)
  File "machine_translation.py", line 161, in simple_attention
    x=attention_weights)
TypeError: sequence_softmax() got an unexpected keyword argument 'x'