src/transformers/convert_slow_tokenizer.py/MBartConverter/vocab
class MBartConverter:    def vocab(self, proto):
        vocab = [
            ("<s>", 0.0),
            ("<pad>", 0.0),
            ("</s>", 0.0),
            ("<unk>", 0.0),
        ]
        vocab += [(piece.piece, piece.score) for piece in proto.pieces[3:]]
        vocab += [
            ("ar_AR", 0.0),
            ("cs_CZ", 0.0),
            ("de_DE", 0.0),
            ("en_XX", 0.0),
            ("es_XX", 0.0),
            ("et_EE", 0.0),
            ("fi_FI", 0.0),
            ("fr_XX", 0.0),
            ("gu_IN", 0.0),
            ("hi_IN", 0.0),
            ("it_IT", 0.0),
            ("ja_XX", 0.0),
            ("kk_KZ", 0.0),
            ("ko_KR", 0.0),
            ("lt_LT", 0.0),
            ("lv_LV", 0.0),
            ("my_MM", 0.0),
            ("ne_NP", 0.0),
            ("nl_XX", 0.0),
            ("ro_RO", 0.0),
            ("ru_RU", 0.0),
            ("si_LK", 0.0),
            ("tr_TR", 0.0),
            ("vi_VN", 0.0),
            ("zh_CN", 0.0),
        ]
        vocab += [("<mask>", 0.0)]
        return vocab