listen method
Calls callback
whenever there is an event. Returns a StreamSubscription
to control the listening.
Implementation
StreamSubscription<T> listen(
dynamic /* Callback | ValueCallback */ callback) {
if (callback is Callback) {
return asStream.listen((_) => callback());
} else if (callback is ValueCallback<T>) {
return asStream.listen(callback);
}
throw Exception('Invalid callback!');
}