public static IUndoState RemoveItem(this UserMagicShopData data, MagicShopItem item, DateTime now) => default;
private static IUndoState UpdateAncientShardPurchaseIfNeeded(this UserMagicShopData data, MagicShopItem item, DateTime now) => default;
public static UserMagicShopData AddItem(this UserMagicShopData data, MagicShopItem item) => default;