import tensorflow as tf

      with tf.variable_scope("root", initializer=tf.constant_initializer(0.5)):
        cell = tf.nn.rnn_cell.GRUCell(2)
        inp = [tf.constant(0.5, shape=[2, 2])] * 2
        enc_outputs, enc_state = tf.nn.rnn(cell, inp, dtype=tf.float32)
        attn_states = tf.concat(1, [tf.reshape(e, [-1, 1, cell.output_size])
                                    for e in enc_outputs])
