refresh method
Implementation
Future<T> refresh() async {
if (state is FutureLoading) {
final result = await _creator();
state = LoadingFuture.value(result);
return result;
} else {
state = LoadingFuture.refreshing(state.value);
final result = await _creator();
state = LoadingFuture.value(result);
return result;
}
}