input: Write a function that provides a command-line interface to download subtitles for movies and TV shows. The function should accept one or more release paths as arguments, and optionally specify the language and subtitle site to use. The available commands are "download", "exist", "test", "list", "help", and "version".
  
  
  def subtitle_cli():
      args = docopt(__doc__, help=True, version='Subtitles Client %s' % __version__)
  
      if args['download']:
          download_subtitles(args['<releases_path>'], args['--engine'], args['--lang'])
      elif args['exist']:
          is_subtitles_exist(args['<releases_path>'], args['--engine'], args['--lang'])
      elif args['test']:
          test_engines(args['<engines>'])
      elif args['--list']:
          for sub_site in SUBTITLE_SITE_LIST.keys():
              sub_dict = SUBTITLE_SITE_LIST.get(sub_site)
              print(sub_dict.get('class_name'))
  
  # Testing the function with different commands
  assert subtitle_cli() == None  # No output expected for help command
  assert download_subtitles(['/path/to/movie'], ['engine1'], 'en') == None  # Simulate download command
  assert is_subtitles_exist(['/path/to/tvshow'], ['engine2'], 'es') == None  # Simulate exist command
  assert test_engines(['engine3']) == None  # Simulate test command
  
output: 
  def subtitle_cli():
      args = docopt(__doc__, help=True, version='Subtitles Client %s' % __version__)
  
      if args['download']:
          download_subtitles(args['<releases_path>'], args['--engine'], args['--lang'])
      elif args['exist']:
          is_subtitles_exist(args['<releases_path>'], args['--engine'], args['--lang'])
      elif args['test']:
          test_engines(args['<engines>'])
      elif args['--list']:
          for sub_site in SUBTITLE_SITE_LIST.keys():
              sub_dict = SUBTITLE_SITE_LIST.get(sub_site)
              print(sub_dict.get('class_name'))
  