Small single parameters.

def mtf_resnet_single():
  """Small single parameters."""
  hparams = mtf_resnet_tiny()
  hparams.mesh_shape = ""
  hparams.layout = ""
  hparams.hidden_size = 32
  hparams.filter_size = 32
  hparams.batch_size = 1
  hparams.num_encoder_layers = 1
  hparams.num_layers = 1
  hparams.block_length = 16
  return hparams