import tensorflow as tf

      raise ValueError("Expected hparams.coupling to be in %s, got %s" %
                       (exp_coupling, self.hparams.coupling))
    if self.is_training:
      init_features = self.create_init_batch(features)
      init_op = self.objective_tower(init_features, init=True)
      init_op = tf.Print(
          init_op, [init_op], message="Triggering data-dependent init.",
          first_n=20)
      tf.add_to_collection("glow_init_op", init_op)
    train_op = self.objective_tower(features, init=False)
