public void Fire(Valet valet)
{
if (!valets.Contains(valet))
{
throw new ValetNotHiredException();
}
valets.Remove(valet);
}
public void Hire(Valet valet)
{
if (valets.Contains(valet))
{
throw new ValetAlreadyHiredException();
}
valets.Add(valet);
}