1. override
void visitChildren(ElementVisitor visitor)

Calls the argument for each child. Must be overridden by subclasses that support having children.

There is no guaranteed order in which the children will be visited, though it should be consistent over time.

Source

@override
void visitChildren(ElementVisitor visitor) {
  if (_materializedChildren == null)
    return;
  for (Element child in _materializedChildren)
    visitor(child);
}