Residual autoencoder model.

def autoencoder_residual():
  """Residual autoencoder model."""
  hparams = autoencoder_autoregressive()
  hparams.optimizer = "Adafactor"
  hparams.clip_grad_norm = 1.0
  hparams.learning_rate_constant = 0.5
  hparams.learning_rate_warmup_steps = 500
  hparams.learning_rate_schedule = "constant * linear_warmup * rsqrt_decay"
  hparams.num_hidden_layers = 5
  hparams.hidden_size = 64
  hparams.max_hidden_size = 1024
  hparams.add_hparam("num_residual_layers", 2)
  hparams.add_hparam("residual_kernel_height", 3)
  hparams.add_hparam("residual_kernel_width", 3)
  hparams.add_hparam("residual_filter_multiplier", 2.0)
  hparams.add_hparam("residual_dropout", 0.2)
  hparams.add_hparam("residual_use_separable_conv", int(True))
  hparams.add_hparam("kl_beta", 1.0)
  return hparams