@SuppressWarnings({ "unchecked", "rawtypes" })
    @CheckReturnValue
    @SchedulerSupport(SchedulerSupport.NONE)
    public static <T> Observable<T> concatEager(ObservableSource<? extends ObservableSource<? extends T>> sources, int maxConcurrency, int prefetch) {
        return wrap(sources).concatMapEager((Function)Functions.identity(), maxConcurrency, prefetch);
    }