How to 'cancel' the stream data response after request another one - flutter

Question

I have a list of Expandable Items, each time I click in one of the items a stream is called returning a list of another items related to that I clicked on. The problem is if I quick expand two items of my initial list, the last remains with the items from the first one.
Example of what is expected:
(EXPANDABLE LIST)
Colombia
(items showed when I click on Colombia)
Bogotá
China
(items showed when I click on China)
Beijing
Example of what happens if I quickly open two items:
(EXPANDABLE LIST)
Colombia (clicked first, and before the load quickly click on China)
China
Bogotá
Is there a way to close or cancel or pause the stream every time I expand one item?
UPDATE
SCREEN
return ExpansionTile(
leading: items[index].image == null || items[index].image.isEmpty ? Image.asset(ASSET_NOIMAGE_URL,
fit: BoxFit.scaleDown
) : Image.network('${BASE_ROUTE_URL}/${ROUTE_SLASH}/${items[index].image}', fit: BoxFit.scaleDown,),
title: Text('${items[index].code} | ${items[index].desc}', style: TextStyle(fontWeight: FontWeight.bold, color: AppColorSecondary),),
children: [
Container(
height: MediaQuery.of(context).size.height * 0.75,
width: MediaQuery.of(context).size.width,
child: CountryDetails(items[index]),
),
],
WIDGET
class _CountryDetailsState extends State<CountryDetails> {
Country country;
#override
void initState() {
country = Provider.of<Country>(context, listen: false);
country.load(produtoGradeFVList: Provider.of<CountryListProvider>(context, listen: false).produtoGradeFVList).then((value) {
}); // here the stream is feed
super.initState();
}

Answer 1

You could set a debounce duration on the stream controller to avoid receiving two requests within a very short interval of time as:
_cityController.stream
.debounceTime(const Duration(milliseconds: 500))
.listen(_handlerFunctionForTapEvent);
Here, _cityController is your StreamController that's listening to the tap events of expandable items from the ui. Try setting a debounce time of 500 milliseconds, hopefully that would fix the issue.
Or you could also send the name of country along with the list of cities in the response from the stream and perform a check in the ui before displaying the city names in the expandable list.