How to get the next available network in a network container?

[napstercc]

Both of these don't work: network = conn.get_object('networkcontainer', {'network_container': '10.88.0.0/13', 'network_view':'default'})

and

network = objects.IPAllocation.next_available_ip_from_cidr('default', '10.88.0.0/13') not sure how to find the next /24 network in this container.