public Subscription[] GetSubscriptions()
 {
     ElementList nl = SelectElements(typeof(Subscription));
     Subscription[] items = new Subscription[nl.Count];
     int i = 0;
     foreach (Element e in nl)
     {
         items[i] = (Subscription) e;
         i++;
     }
     return items;
 }
 /// <summary>
 /// 
 /// </summary>
 /// <param name="item"></param>
 /// <returns></returns>
 public Subscription AddSubscription(Subscription sub)
 {
     AddChild(sub);
     return sub;
 }
 /// <summary>
 /// 
 /// </summary>
 /// <returns></returns>
 public Subscription AddSubscription()
 {
     Subscription sub = new Subscription();
     AddChild(sub);
     return sub;
 }