public ActionResult Form(Contact contact)
 {
     if (ModelState.IsValid)
     {
         if (contactService.ContactExists(contact.Id) && contact.Id > 0)
         {
             contactService.EditContact(contact);
         }
         else
         {
             contactService.AddContact(contact);
         }
         return(RedirectToAction("Index"));
     }
     else
     {
         return(View(contact));
     }
 }