call method
Implementation
void call(bool expanded) {
  if (expanded) {
    onChanged(nodes.expandNode(target));
  } else {
    onChanged(nodes.collapseNode(target));
  }
}void call(bool expanded) {
  if (expanded) {
    onChanged(nodes.expandNode(target));
  } else {
    onChanged(nodes.collapseNode(target));
  }
}