public void SetChild(string num, Item item)
 {
     _children[num] = item;
     MethodChanged?.Invoke(this, new MethodChangedEventArgs(nameof(GetChild), args => args[0].Equals(num)));
 }
 public void RaiseMethodChanged(string methodName, Func <object[], bool> predicate)
 {
     MethodChanged?.Invoke(this, new MethodChangedEventArgs(methodName, predicate));
 }