return New(pr, func(max int, rangeSpec string, offset int) (allocator.Interface, error) {
		return allocator.NewAllocationMapWithOffset(max, rangeSpec, offset), nil
	})
}

// NewFromSnapshot allocates a PortAllocator and initializes it from a snapshot.
func NewFromSnapshot(snap *api.RangeAllocation) (*PortAllocator, error) {
	pr, err := net.ParsePortRange(snap.Range)
	if err != nil {
		return nil, err
	}
	r, err := NewInMemory(*pr)