code: def update_policy(self, scaling_group, policy, name=None, policy_type=None,
              cooldown=None, change=None, is_percent=False,
              desired_capacity=None, args=None):
          
          return self._manager.update_policy(scaling_group, policy, name=name,
                  policy_type=policy_type, cooldown=cooldown, change=change,
                  is_percent=is_percent, desired_capacity=desired_capacity,
                  args=args)
docs: Updates the specified policy. One or more of the parameters may be
          specified.