def build_criterion(self, cfg: DictConfig):
        """
        Build the :class:`~fairseq.criterions.FairseqCriterion` instance for
        this task.

        Args:
            cfg (omegaconf.DictConfig): configration object

        Returns:
            a :class:`~fairseq.criterions.FairseqCriterion` instance
        """
        from fairseq import criterions

        return criterions.build_criterion(cfg, self)

        Build the :class:`~fairseq.criterions.FairseqCriterion` instance for
        this task.

        Args:
            cfg (omegaconf.DictConfig): configration object

        Returns:
            a :class:`~fairseq.criterions.FairseqCriterion` instance
        
decoding/IAD/fairseq/fairseq/tasks/fairseq_task.py