public void RulesTest()
        {
            Arithmetic <int> defaultArithmetic = Arithmetic <int> .Default;
            Arithmetic <int> arithmetic1       =
                defaultArithmetic.ApplyRules(new ArithmeticRules(NullBehavior.ThreatNullAsNull, OverflowBehavior.AllowOverflow));
            Arithmetic <int> arithmetic2 =
                arithmetic1.ApplyRules(new ArithmeticRules(NullBehavior.ThreatNullAsZero, OverflowBehavior.DenyOverflow));
            Arithmetic <int> arithmetic3 =
                defaultArithmetic.ApplyRules(new ArithmeticRules(NullBehavior.ThreatNullAsNull, OverflowBehavior.AllowOverflow));

            Assert.AreEqual(arithmetic1, arithmetic3);
            Assert.AreNotEqual(arithmetic1, arithmetic2);
        }