// POST api/employees
        public void Post(Employee employee)
        {
            int maxId = list.Max(e => e.Id);
            employee.Id = maxId + 1;

            list.Add(employee);
        }
 // PUT api/employees/12345
 public void Put(int id, Employee employee)
 {
     int index = list.ToList().FindIndex(e => e.Id == id);
     list[index] = employee;
 }