protected internal BaseCard(double turnover, CardHolder cardHolder)
{
Turnover = turnover;
}
public GoldCard(double turnover, CardHolder cardHolder) : base(turnover, cardHolder)
{
CardHolder = cardHolder == null ? throw new NullReferenceException() : cardHolder;
}
protected CardHolder(CardHolder cardHolder)
{
FirstName = cardHolder.FirstName;
LastName = cardHolder.LastName;
}