import tensorflow as tf

            cell_bw = tf.contrib.rnn.GRUCell(embed_size // 2)
            outputs, _ = tf.nn.bidirectional_dynamic_rnn(cell, cell_bw, dec, dtype=tf.float32)
            outputs = tf.concat(outputs, 2)
        self.Z_hat = tf.layers.dense(outputs, 1 + fourier_window_size // 2)
