public void then_two_plus_two_is_four()
        {
            var sut = new Calculator();             //Given the calculator
            var result = sut.Add(2, 2);             //When 0 is added to 0

            Assert.That(result, Is.EqualTo(4));     //Then the result is 0
        }
        public void then_one_plus_one_is_two()
        {
            var sut = new Calculator();             //Given the calculator
            var result = sut.Add(1, 1);             //When 0 is added to 0

            Assert.That(result, Is.EqualTo(2));     //Then the result is 0
        }
        public void then_zero_plus_zero_is_zero()
        {
            var sut = new Calculator();             //Given the calculator
            var result = sut.Add(0, 0);             //When 0 is added to 0

            Assert.That(result, Is.EqualTo(0));     //Then the result is 0
        }