public void ExcludeSets()
        {
            var seta = new ImmutableSet64().Add(1, 2, 4, 8, 16, 32);
            var setb = new ImmutableSet64().Add(1, 2, 3, 4, 5);

            seta.Except(setb)
            .SequenceEqual(new int[] { 8, 16, 32 })
            .Should()
            .BeTrue();
        }
        public void ExcludeEnumerable()
        {
            IImmutableSet <int> seta = new ImmutableSet64().Add(1, 2, 4, 8, 16, 32);
            var setb = Enumerable.Range(1, 5);

            seta.Except(setb)
            .SequenceEqual(new int[] { 8, 16, 32 })
            .Should()
            .BeTrue();
        }