listen method
Implementation
StreamSubscription<T> listen(
void Function(T event)? onData, {
Function? onError,
void Function()? onDone,
bool? cancelOnError,
bool async = false,
}) {
final StreamSubscriptionUnit<T> sub;
if (async) {
sub = _StreamSubscriptionAsyncUnit<T>(this, onData,
onError: onError, onDone: onDone, cancelOnError: cancelOnError);
} else {
sub = StreamSubscriptionUnit<T>(this, onData,
onError: onError, onDone: onDone, cancelOnError: cancelOnError);
}
if (_canceled) {
onListen(sub);
sub.sendDone();
} else {
_onListen(sub);
}
return sub;
}