src/transformers/models/mbart50/tokenization_mbart50_fast.py/MBart50TokenizerFast/as_target_tokenizer
class MBart50TokenizerFast:    def as_target_tokenizer(self):
        """
        Temporarily sets the tokenizer for encoding the targets. Useful for tokenizer associated to
        sequence-to-sequence models that need a slightly different processing for the labels.
        """
        self.set_tgt_lang_special_tokens(self.tgt_lang)
        yield
        self.set_src_lang_special_tokens(self.src_lang)