public void ParseNumbers4()
        {
            var input    = " , ";
            var shouldBe = new int[0];
            var reallyIs = StupidMaths.ParseNumbers(input);

            CollectionAssert.AreEqual(shouldBe, reallyIs);
        }
        public void ParseNumbers5()
        {
            var input    = "ж, о, п, 2  5    а";
            var shouldBe = new[] { 2, 5 };
            var reallyIs = StupidMaths.ParseNumbers(input);

            CollectionAssert.AreEqual(shouldBe, reallyIs);
        }
        public void ParseNumbers2()
        {
            var input    = "1";
            var shouldBe = new[] { 1 };
            var reallyIs = StupidMaths.ParseNumbers(input);

            CollectionAssert.AreEqual(shouldBe, reallyIs);
        }