input: from typing import List
  
  
  def subtitles_client(command: str, releases_path: List[str], lang: str = None, engines: List[str] = None) -> None:
      """
      A command-line interface to download subtitles for movies and TV shows.
      Available commands are "download", "exist", "test", "list", "help", and "version".
  
      >>> subtitles_client("download", ["/path/to/movie"], lang="en", engines=["site1"])
      [<engine_output>]
      >>> subtitles_client("exist", ["/path/to/tvshow"], lang="en", engines=["site1"])
      [<engine_output>]
      """
  
output:     
      if command == "download":
          for path in releases_path:
              for engine in engines:
                  print(f"Downloading subtitles for {path} using {engine} engine...")
                  # Simulate downloading process
                  print(f"Subtitles downloaded for {path} using {engine} engine.")
      elif command == "exist":
          for path in releases_path:
              for engine in engines:
                  print(f"Checking if subtitles exist for {path} using {engine} engine...")
                  # Simulate checking process
                  print(f"Subtitles exist for {path} using {engine} engine.")
      elif command == "test":
          print("Testing engines...")
          for engine in engines:
              print(f"Testing {engine} engine...")
              # Simulate testing process
              print(f"{engine} engine tested successfully.")
      elif command == "list":
          print("Listing available engines...")
          for engine in engines:
              print(engine)
      elif command == "help":
          print("Available commands: download, exist, test, list, help, version")
      elif command == "version":
          print("Subtitles Client v1.0")
      else:
          print(f"Unknown command: {command}")
  