'Return the top states from encoder for decoder.
Args:
sess: tensorflow session.
enc_inputs: encoder inputs of shape [batch_size, enc_timesteps].
enc_len: encoder input length of shape [batch_size]
Returns:
enc_top_states: The top level encoder states.
dec_in_state: The decoder layer initial state.'

def encode_top_state(self, sess, enc_inputs, enc_len):

    results = sess.run([self._enc_top_states, self._dec_in_state], feed_dict={self._articles: enc_inputs, self._article_lens: enc_len})
    return (results[0], results[1][0])
