import tensorflow as tf

          logits=logits, labels=index)
        log_prob += curr_log_prob
        curr_ent = tf.stop_gradient(tf.nn.softmax_cross_entropy_with_logits(
          logits=logits, labels=tf.nn.softmax(logits)))
        entropy += curr_ent
        prev_layers.append(anchors.read(tf.reduce_sum(index)))
        inputs = prev_layers[-1]

      for i in range(2):  # op_1, op_2
        next_c, next_h = stack_lstm(inputs, prev_c, prev_h, self.w_lstm)
