broadcaster<T> method
Creates a StreamController.broadcast that is closed within dispose.
Implementation
StreamController<T> broadcaster<T>({FutureOr<void> Function()? onCancel /*?*/
}) {
_sanity();
final ret = ControlledStreamController<T>.broadcast(onCancel: onCancel);
ret.done.then((ev) => _ctrls.remove(ret));
_ctrls.add(ret);
return ret;
}