def add_args(parser):
        """Add criterion-specific arguments to the parser."""
        parser.add_argument(
            "--label-smoothing",
            default=0.0,
            type=float,
            metavar="D",
            help="epsilon for label smoothing, 0 means no label smoothing",
        )
Add criterion-specific arguments to the parser.
decoding/GAD/fairseq/criterions/nat_loss.py