findAncestorStateOfType<T extends State<StatefulComponent> >  method 
Implementation
@override
T? findAncestorStateOfType<T extends State<StatefulComponent>>() {
  var ancestor = _parent;
  while (ancestor != null &&
      !(ancestor is StatefulBinding && ancestor.state is T)) {
    ancestor = ancestor._parent;
  }
  return (ancestor as StatefulBinding?)?.state as T?;
}