Flutter Algolia search multiple indices - flutter

Question

Inside my Algolia application I have to indices which both contain users. Both of them must have a uid and a username (along other fields). I managed to implement the search for on of the indices. But how can I search in both indices?
I followed this tutorial but it does not say anything about searching multiple indices.
I found this about searching multiple indices but how can I do that in Flutter in combination with `Hits Searcher and infinite_scrolling_pagination.
This is my setup:
Stream<SearchMetadata> get _searchUsersMetadata =>
_userSearcher.responses.map(
SearchMetadata.fromResponse,
);
final PagingController<int, AlgoliaUser> _pagingController =
PagingController(firstPageKey: 0);
#override
void initState() {
super.initState();
_searchPage.listen((page) {
if (page.pageKey == 0) {
_pagingController.refresh();
}
_pagingController.appendPage(page.items, page.nextPageKey);
}).onError((error) => _pagingController.error = error);
_pagingController.addPageRequestListener(
(pageKey) => _userSearcher.applyState(
(state) => state.copyWith(page: pageKey),
),
);
}
final _userSearcher = HitsSearcher(
applicationID: 'myAppID',
apiKey: 'myApiKey',
indexName: 'users',
);
Stream<HitsPage> get _searchPage => _userSearcher.responses.map(
HitsPage.fromResponse,
);
_onSearchChanged(String query) {
if (_debounce?.isActive ?? false) {
_debounce?.cancel();
}
_debounce = Timer(const Duration(milliseconds: 500), () {
_userSearcher.applyState(
(state) => state.copyWith(
query: _searchTextEditingController.text,
page: 0,
),
);
});
}