func (r *Instance) Locator(api *API) *InstanceLocator {
	for _, l := range r.Links {
		if l["rel"] == "self" {
			return api.InstanceLocator(l["href"])
		}
	}
	return nil
}
func (r *Instance) Locator(api *API) *InstanceLocator {
	for _, l := range r.Links {
		if l["rel"] == "self" {
			return api.InstanceLocator(l["href"])
		}
	}
	return nil
}
// Locator returns a locator for the given resource