Creates a scheduled scaling action for a Auto Scaling group. If you
        leave a parameter unspecified, the corresponding value remains
        unchanged in the affected Auto Scaling group.

        :type as_group: string
        :param as_group: The auto scaling group to get activities on.

        :type name: string
        :param name: Scheduled action name.

        :type time: datetime.datetime
        :param time: The time for this action to start.

        :type desired_capacity: int
        :param desired_capacity: The number of EC2 instances that should
            be running in this group.

        :type min_size: int
        :param min_size: The minimum size for the new auto scaling group.

        :type max_size: int
        :param max_size: The minimum size for the new auto scaling group.

def create_scheduled_group_action(self, as_group, name, time,
                                      desired_capacity=None,
                                      min_size=None, max_size=None):
        """
        Creates a scheduled scaling action for a Auto Scaling group. If you
        leave a parameter unspecified, the corresponding value remains
        unchanged in the affected Auto Scaling group.

        :type as_group: string
        :param as_group: The auto scaling group to get activities on.

        :type name: string
        :param name: Scheduled action name.

        :type time: datetime.datetime
        :param time: The time for this action to start.

        :type desired_capacity: int
        :param desired_capacity: The number of EC2 instances that should
            be running in this group.

        :type min_size: int
        :param min_size: The minimum size for the new auto scaling group.

        :type max_size: int
        :param max_size: The minimum size for the new auto scaling group.
        """
        params = {'AutoScalingGroupName': as_group,
                  'ScheduledActionName': name,
                  'Time': time.isoformat()}
        if desired_capacity is not None:
            params['DesiredCapacity'] = desired_capacity
        if min_size is not None:
            params['MinSize'] = min_size
        if max_size is not None:
            params['MaxSize'] = max_size
        return self.get_status('PutScheduledUpdateGroupAction', params)