input: 下面是根据你提供的段落生成的问题，使用给定的格式：
  
  txt
  What should be the expected output of the `download_subtitles` function when called with `[“Sting_1993”]`, `[“engine1”]`, and `“en”` as arguments in the Subtitles Client script?
  
  
  请注意，问题可能不正确或不符合预期，因为你没有给出 `download_subtitles` 函数的具体输出示例。如果你需要更准确的示例，请提供更多细节。
output:     
      for video in videos:
          for engine in engines:
              subtitles = client.download_subtitles(video, engine, language)
              if subtitles:
                  return subtitles
      return None
  