fetchNextTrains function
Fetches the next trains for the given station codes.
apiKey is your API key for the WMATA API.
If stationCodes is null, then all stations will be returned.
Implementation
Future<List<NextTrain>> fetchNextTrains(
String apiKey, {
List<String>? stationCodes,
}) async =>
NextTrainsService.fetchNextTrains(
apiKey,
stationCodes: stationCodes == null ? 'All' : stationCodes.join(','),
);