Add attention to the model

[ckcz123]

What if I'd like to use attention_decoder instead of rnn_decoder?

I wonder how to modify outputs, last_state = seq2seq.rnn_decoder(inputs, self.initial_state, cell, loop_function=loop if infer else None, scope='rnnlm').

What should attention_states be?

[john-parton]

I believe you can add

self.cell = cell = rnn.AttentionCellWrapper(cell, attn_length, state_is_tuple=True)

after

self.cell = cell = rnn.MultiRNNCell(cells, state_is_tuple=True)