Create the latent tower.

def construct_latent_tower(self, images, time_axis):
    """Create the latent tower."""
    # No latent in the first phase
    first_phase = tf.less(
        self.get_iteration_num(), self.hparams.num_iterations_1st_stage)

    # use all frames by default but this allows more
    # predicted frames at inference time
    latent_num_frames = self.hparams.latent_num_frames
    tf.logging.info("Creating latent tower with %d frames." % latent_num_frames)
    if latent_num_frames > 0:
      images = images[:, :latent_num_frames]

    return common_video.conv_latent_tower(
        images=images,
        time_axis=time_axis,
        latent_channels=self.hparams.latent_channels,
        min_logvar=self.hparams.latent_std_min,
        is_training=self.is_training,
        random_latent=first_phase,
        tiny_mode=self.hparams.tiny_mode,
        small_mode=self.hparams.small_mode)