attach method
Implementation
@override
void attach(covariant RenderObject child, {covariant RenderObject? after}) {
if (child is ChildSlotRenderObject) {
assert(
isAttached ? _realNodeOf(parent!).contains(child.node) : node.contains(child.node),
'Cannot attach a child that is not already part of the component fragment.',
);
child.parent = this;
child.finalize();
return;
}
throw UnsupportedError('SlottedDomRenderObject cannot have children attached to them.');
}