    def add_args(parser):
        """Add task-specific arguments to the parser."""
        # fmt: off
        parser.add_argument('-s', '--source-lang', default=None, metavar='SRC',
                            help='inference source language')
        parser.add_argument('-t', '--target-lang', default=None, metavar='TARGET',
                            help='inference target language')
        parser.add_argument('--lang-pairs', default=None, metavar='PAIRS',
                            help='comma-separated list of language pairs (in training order): en-de,en-fr,de-fr',
                            action=FileContentsAction)
        parser.add_argument('--keep-inference-langtok', action='store_true',
                            help='keep language tokens in inference output (e.g. for analysis or debugging)')

        SamplingMethod.add_arguments(parser)
        MultilingualDatasetManager.add_args(parser)
Add task-specific arguments to the parser.
fairseq/tasks/translation_multi_simple_epoch.py