code: def _concat_nbest_translations(translations: List[Translation], stop_ids: Set[int],
                                 length_penalty: LengthPenalty,
                                 brevity_penalty: Optional[BrevityPenalty] = None) -> Translation:
      
      expanded_translations = (_expand_nbest_translation(translation) for translation in translations)
  
      concatenated_translations = []  # type: List[Translation]
  
      for translations_to_concat in zip(*expanded_translations):
          concatenated_translations.append(_concat_translations(translations=list(translations_to_concat),
                                                                stop_ids=stop_ids,
                                                                length_penalty=length_penalty,
                                                                brevity_penalty=brevity_penalty))
  
      return _reduce_nbest_translations(concatenated_translations)
docs: Combines nbest translations through concatenation.
  
      :param translations: A list of translations (sequence starting with BOS symbol,
          attention_matrix), score and length.
      :param stop_ids: The EOS symbols.
      :param length_penalty: LengthPenalty.
      :param brevity_penalty: Optional BrevityPenalty.
      :return: A concatenation of the translations with a score.