How to use get_web_session()?

My code is
LOG.info("-"*30)
LOG.info("Logged on as: %s", client.user.name)
LOG.info("Community profile: %s", client.steam_id.community_url)
LOG.info("Last logon: %s", client.user.last_logon)
LOG.info("Last logoff: %s", client.user.last_logoff)
LOG.info("-"*30)
webs = Web(client)
req = webs.get_web_session()
but
TypeError: object.init() takes exactly one argument (the instance to initialize)