public static ListCalculator BuildListCalculator()
        {
            var tokeniser = new StringTokeniser();

            return new ListCalculator(tokeniser);
        }
        public static ShuntingYardCalculator BuildShuntingYardCalculator()
        {
            var tokeniser = new StringTokeniser();

            return new ShuntingYardCalculator(tokeniser);
        }
        public static StackCalculator BuildStackCalculator()
        {
            var tokeniser = new StringTokeniser();

            return new StackCalculator(tokeniser);
        }
 public void SetUp()
 {
     string input = "500+10+(5/1)";
     var tokeniser = new StringTokeniser();
     _tokens = tokeniser.Convert(input).ToList();
 }