public void TestIntersectWith()
{
var a = new RedBlackSetTester<int>(_even);
Assert.That(() => a.IntersectWith(null), Throws.InstanceOf<ArgumentNullException>());
a.IntersectWith(_primes);
Assert.That(a, Has.Count.EqualTo(1));
Assert.That(a.Contains(2));
a.IntersectWith(_odd);
Assert.That(a, Is.Empty);
}