input: Write a function to implement the command-line interface for downloading subtitles from movies and TV shows. The function should accept the command type ("download", "exist", "test", "list", "help", "version") and additional parameters such as release paths, language, and subtitle site. The function should execute the appropriate command based on the input and print the relevant output.
  assert main({"download": True, "<releases_path>": ["path1", "path2"], "--engine": ["site1"], "--lang": "en"})
  assert main({"exist": True, "<releases_path>": ["path1"], "--engine": ["site2"], "--lang": "fr"})
  assert main({"test": True, "<engines>": ["site1", "site3"]})
  assert main({"--list": True})
  assert main({"--help": True})
  assert main({"--version": True})
output: def main(command):
      if "download" in command:
          print(f"Downloading subtitles for {command['<releases_path>']} from {command['--engine']} in {command['--lang']}")
      elif "exist" in command:
          print(f"Checking existence of subtitles for {command['<releases_path>']} from {command['--engine']} in {command['--lang']}")
      elif "test" in command:
          print(f"Testing engines: {command['<engines>']}")
      elif "--list" in command:
          print("Listing available engines")
      elif "--help" in command:
          print("Displaying help information")
      elif "--version" in command:
          print("Displaying version information")