def advance(self):
        """
        When called, returns the token that would take this constraint one step closer to being fulfilled.

        Return:
            token_ids(`torch.tensor`): Must be a tensor of a list of indexable tokens, not some integer.
        """
        raise NotImplementedError(
            f"{self.__class__} is an abstract class. Only classes inheriting this class can be called."
        )

        When called, returns the token that would take this constraint one step closer to being fulfilled.

        Return:
            token_ids(`torch.tensor`): Must be a tensor of a list of indexable tokens, not some integer.
        
dpkd/transformers/src/transformers/generation/beam_constraints.py