    def add_args(parser):
        """Add model-specific arguments to the parser."""
        # fmt: off
        TransformerModel.add_args(parser)
        parser.add_argument('--alignment-heads', type=int, metavar='N',
                            help='number of attention heads to be used for '
                                 'pointing')
        parser.add_argument('--alignment-layer', type=int, metavar='I',
                            help='layer number to be used for pointing (0 '
                                 'corresponding to the bottommost layer)')
        parser.add_argument('--source-position-markers', type=int, metavar='N',
                            help='dictionary includes N additional items that '
                                 'represent an OOV token at a particular input '
                                 'position')
        parser.add_argument('--force-generation', type=float, metavar='P',
                            default=None,
                            help='set the vocabulary distribution weight to P, '
                                 'instead of predicting it from the input (1.0 '
                                 'corresponding to generation, 0.0 to pointing)')
Add model-specific arguments to the parser.
examples/pointer_generator/pointer_generator_src/transformer_pg.py