public void DetermineEquality()
        {
            var set = new ImmutableSet64().Add(1, 2, 3);

            set.SetEquals(new ImmutableSet64().Add(1, 2, 3)).Should().BeTrue();
            set.Equals(new ImmutableSet64().Add(1, 2, 3)).Should().BeTrue();
            set.Equals(14ul).Should().BeTrue();
        }
        public void DetermineEqualityWithEnumerable()
        {
            IImmutableSet <int> set = new ImmutableSet64().Add(1, 2, 3);

            set.SetEquals(Enumerable.Range(1, 3)).Should().BeTrue();
        }