Creates a new list for a client.

def create(self, client_id, title, unsubscribe_page, confirmed_opt_in,
               confirmation_success_page, unsubscribe_setting="AllClientLists"):
        """Creates a new list for a client."""
        body = {
            "Title": title,
            "UnsubscribePage": unsubscribe_page,
            "ConfirmedOptIn": confirmed_opt_in,
            "ConfirmationSuccessPage": confirmation_success_page,
            "UnsubscribeSetting": unsubscribe_setting}
        response = self._post("/lists/%s.json" % client_id, json.dumps(body))
        self.list_id = json_to_py(response)
        return self.list_id