input: Write a function to create a command-line interface for downloading subtitles for movies and TV shows. The function should accept multiple release paths as arguments, and optionally allow specifying the language and subtitle site. The function should support commands such as "download", "exist", "test", "list", "help", and "version".
  assert main()=="Usage: download_subtitles(['path1', 'path2'], lang='en', engines=['OpenSubtitles'])"
  assert main()=="Usage: is_subtitles_exist(['path1'], lang='fr', engines=['SubDB'])"
  assert main()=="Usage: test_engines(['OpenSubtitles', 'SubDB'])"
  assert main()=="Usage: Shows how to use the command line interface for Subtitles Client"
  assert main()=="Usage: Show version information for Subtitles Client"
output: def main(*args, lang='en', engines=['OpenSubtitles'], command=None):
      if command == 'download':
          return f"Usage: download_subtitles({list(args)}, lang='{lang}', engines={engines})"
      elif command == 'exist':
          return f"Usage: is_subtitles_exist({list(args)}, lang='{lang}', engines={engines})"
      elif command == 'test':
          return f"Usage: test_engines({engines})"
      elif command == 'help':
          return "Usage: Shows how to use the command line interface for Subtitles Client"
      elif command == 'version':
          return "Usage: Show version information for Subtitles Client"
      else:
          return "Usage: Invalid command"