public void Should_Give_Average()
        {
            var result = _calculator.Average(4, 10);

            Assert.AreEqual(result, 7, "(4+10)/2 should be 7.");
        }
        public void Should_Average()
        {
            var result = _calculator.Average(3, 7);

            Assert.AreEqual(result, 5, "(3 + 7) / 2 = 5");
        }