def get_steam():
  helper = lambda udd: Steam(udd) if os.path.exists(udd) else None
  plat = platform.system()
  if plat == 'Darwin':
    return helper(paths.default_osx_userdata_path())
  if plat == 'Linux':
    return helper(paths.default_linux_userdata_path())
  if plat == 'Windows':
    possible_dir = winutils.find_userdata_directory()
    return helper(possible_dir) if possible_dir is not None else None
  return None