import tensorflow as tf

            init_fw = tf.tile(tf.Variable(
                tf.zeros([1, 1, num_units])), [1, batch_size, 1])
            init_bw = tf.tile(tf.Variable(
                tf.zeros([1, 1, num_units])), [1, batch_size, 1])
            mask_fw = dropout(tf.ones([1, batch_size, input_size_], dtype=tf.float32),
                              keep_prob=keep_prob, is_train=is_train, mode=None)
            mask_bw = dropout(tf.ones([1, batch_size, input_size_], dtype=tf.float32),
                              keep_prob=keep_prob, is_train=is_train, mode=None)
            self.grus.append((gru_fw, gru_bw, ))
            self.inits.append((init_fw, init_bw, ))
            self.dropout_mask.append((mask_fw, mask_bw, ))

