insertAll method
Insert a collection of Iterable nodes in the children list at index
The ValueListenable and insertedNodes listeners will also be notified on this operation
Implementation
void insertAll(int index, Iterable<IndexedNode> iterable) {
super.insertAll(index, iterable);
_notifyListeners();
_notifyNodesInserted(NodeInsertEvent(List.from(iterable), index));
}