code: def exists(config):
      
      exists = (
          pathlib.Path(config.cache_path).exists()
          and pathlib.Path(config.cache_path).is_dir()
      )
      if not exists:
          return False
      index_path = pathlib.Path(config.cache_path) / "index.json"
      if index_path.exists():
          with open(index_path, "r") as out:
              index = json.load(out)
          if index["version"] != __version__:
              # TODO: Inspect the versions properly.
              logger.warning(
                  "Wily cache is old, you may incur errors until you rebuild the cache."
              )
      else:
          logger.warning(
              "Wily cache was not versioned, you may incur errors until you rebuild the cache."
          )
          create_index(config)
      return True
docs: Check whether the .wily/ directory exists.
  
      :param config: The configuration
      :type  config: :class:`wily.config.WilyConfig`
  
      :return: Whether the .wily directory exists
      :rtype: ``boolean``