public void Complement()
{
var s1 = new Set<int>() { 1, 2, 3, 4, 5 };
var s2 = new Set<int>() { 2, 4, 5, 6, 8, 10 };
var s3 = s1.Complement(s2);
Console.Out.WriteLine(s3);
Assert.That(s3, Has.Count.EqualTo(2), "Incorrect number of elements.");
Assert.That(s3, Has.Member(1), "Missing element.");
Assert.That(s3, Has.No.Member(10), "Element should not be present.");
}