import tensorflow as tf

    fake_loss = tf.reduce_sum(tf.square(logits))
    grad_norms = [
        _get_grad_norm(
            fake_loss, tf.trainable_variables('.*/progressive_gan_block_1/.*')),
        _get_grad_norm(
            fake_loss, tf.trainable_variables('.*/progressive_gan_block_2/.*')),
        _get_grad_norm(
            fake_loss, tf.trainable_variables('.*/progressive_gan_block_3/.*'))
    ]

    grad_norms_output = None
    with self.test_session(use_gpu=True) as sess:
      sess.run(tf.global_variables_initializer())
      grad_norms_output = np.array([
