public ListChangedEventArgs(ListChangedType listChangedType, int newIndex, int oldIndex) {
Debug.Assert(listChangedType != ListChangedType.PropertyDescriptorAdded, "this constructor is used only for item changed in the list");
Debug.Assert(listChangedType != ListChangedType.PropertyDescriptorDeleted, "this constructor is used only for item changed in the list");
Debug.Assert(listChangedType != ListChangedType.PropertyDescriptorChanged, "this constructor is used only for item changed in the list");
this.listChangedType = listChangedType;
this.newIndex = newIndex;
this.oldIndex = oldIndex;
}