    def collater(self, samples):
        """Merge a list of samples to form a mini-batch.

        Args:
            samples (List[dict]): samples to collate

        Returns:
            dict: a mini-batch suitable for forwarding with a Model
        """
        raise NotImplementedError
Merge a list of samples to form a mini-batch.

Args:
samples (List[dict]): samples to collate

Returns:
dict: a mini-batch suitable for forwarding with a Model
fairseq/data/fairseq_dataset.py