public async Task UnionShouldWork()
{
var sequence1 = AsyncEnumerable.Range(0, 100);
var sequence2 = AsyncEnumerable.Range(0, 200);
var sequence3 = Enumerable.Range(0, 200).ToList();
var sequence4 = await sequence1.Union(sequence2).ToList();
CollectionAssert.AreEqual(sequence3,sequence4.ToList());
}
}