from tensorflow.contrib.layers.python.layers import utils


    def build_no_ops():
      return (tf.no_op(), tf.no_op())

    # Only make the ops if we know that `is_training=True`, or the value of
    # `is_training` is unknown.
    is_training_const = utils.constant_value(is_training)
    if is_training_const is None or is_training_const:
      update_mean_op, update_second_moment_op = utils.smart_cond(
          is_training,
          build_update_ops,
          build_no_ops,
