import tensorflow as tf

            attn_mask = tf.logical_and(direct_mask_tile, rep_mask_tile, name='attn_mask')  # bs,bn,bl,bl

            # attention
            f_bias = tf.get_variable('f_bias', [ivec], tf.float32, tf.constant_initializer(0.))
            dependent_head = linear(
                rep_map, 2 * ivec, False, 0., 'linear_dependent_head', False, wd, keep_prob, is_train)  # bs,bn,bl,2vec
