type PortRangeVar struct {
	Val *string
}

// Set sets the flag value
func (v PortRangeVar) Set(s string) error {
	if _, err := utilnet.ParsePortRange(s); err != nil {
		return fmt.Errorf("%q is not a valid port range: %v", s, err)
	}
	if v.Val == nil {
		// it's okay to panic here since this is programmer error

	})
}

// 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)
	if err != nil {
		return nil, err
	}
	if err := r.Restore(*pr, snap.Data); err != nil {
		return nil, err
	}