}
	for k, v := range d.Cache {
		clone.Cache[k] = v.clone()
	}
	return clone
}

// merge root of other into d.
// children of root will be flattened before being merged.
// Last update time will be set to the last updated.
func (d *dataUsageCache) merge(other dataUsageCache) {
	existingRoot := d.root()
	otherRoot := other.root()
	if existingRoot == nil && otherRoot == nil {
		return