public ActionResult LeapYears(LeapYearSearchTool searchTool)
        {
            if (ModelState.IsValidField("EndYear") && searchTool.StartYear >= searchTool.EndYear)
            {
                ModelState.AddModelError("EndYear", "Please make sure your end date is later than your start date");
            }
            if (ModelState.IsValid)
            {
                var leapFinder = new LeapYearFinder();
                var leapYears = new LeapYears();

                leapYears.StartYear = searchTool.StartYear.Value;
                leapYears.EndYear = searchTool.EndYear.Value;

                var result = leapFinder.SearchForLeapYears(leapYears);

                searchTool.Years = result.Years;
                searchTool.IsPostback = true;
                return View("LeapYears", searchTool);

            }
            else
            {
                searchTool.Years = new List<int>(); //not sure why this is necessary but I get null ref exception on View without it.

                return View("LeapYears", searchTool);
            }
        }
 public ActionResult LeapYears()
 {
     var model = new LeapYearSearchTool();
     return View(model);
 }