input: 
  def download_subtitles(releases, engines=[DEFAULTS['subtitle_engine']], lang=DEFAULTS['subtitle_language']):
      """
      Downloads subtitles for the provided releases using specified subtitle engines and language.
      
      >>> download_subtitles(['/path/to/movie1', '/path/to/movie2'], ['opensubtitles', 'subscene'], 'en')
      """
  
output:     subtitles = []
      for release in releases:
          for engine in engines:
              subtitle = fetch_subtitle(release, engine, lang)
              if subtitle:
                  subtitles.append(subtitle)
                  break
      return subtitles