func (h dataUsageHash) String() string {
	return string(h)
}

// Key returns the key.
func (h dataUsageHash) Key() string {
	return string(h)
}

func (d *dataUsageCache) flattenChildrens(root dataUsageEntry) (m map[string]dataUsageEntry) {
	m = make(map[string]dataUsageEntry)
	for id := range root.Children {
		e := d.Cache[id]
		if len(e.Children) > 0 {
			e = d.flatten(e)
		}
		m[id] = e