public static IAsyncEnumerable <TSource> Concat <TSource>(this IAsyncEnumerable <TSource> first, IAsyncEnumerable <TSource> second) => LinqEnumerable.Concat(first, second);
public static IAsyncEnumerable <TSource> Concat <TSource>(this IAsyncEnumerable <TSource> first, IAsyncEnumerable <TSource> second) => LinqEnumerable.Concat(first, second);