def add_args(parser):
        """Add criterion-specific arguments to the parser."""
        # fmt: off
        parser.add_argument('--underlying-criterion', type=str, metavar='VAL', required=True,
                            help='underlying criterion to use for the composite loss')
        # fmt: on
Add criterion-specific arguments to the parser.
understand_icl/fairseq/fairseq/criterions/composite_loss.py