onDone method Null safety
- void handleDone(
Replaces the done event handler of this subscription.
handleDone function is called when the stream closes.
The value may be
null, in which case no function is called.
This method replaces the current handler set by the invocation of Stream.listen, by calling asFuture, or by a previous call to onDone.
void onDone(void handleDone()?);