Dominion.PlayerState.RequestPlayerTopDeckCardFromPlay C# (CSharp) Method

        internal Card RequestPlayerTopDeckCardFromPlay(GameState gameState, CardPredicate acceptableCard, bool isOptional)
        {
            if (!this.cardsPlayed.HasCard(acceptableCard))
            {
                return null;
            }

            Card cardTypeToTopDeck = this.actions.GetCardFromPlayToTopDeckDuringCleanup(gameState, acceptableCard, isOptional);
            if (cardTypeToTopDeck == null)
            {
                if (isOptional)
                {
                    return null;
                }
                else
                {
                    throw new Exception("Player must choose a card to top deck");
                }
            }

            Card cardToTopDeck = this.cardsPlayed.RemoveCard(cardTypeToTopDeck);
            if (cardToTopDeck == null)
            {
                throw new Exception("Could not remove Card From Hand");
            }

            if (!acceptableCard(cardToTopDeck))
            {
                throw new Exception("Card does not meet constraint for top deck");
            }

            this.gameLog.PlayerTopDeckedCard(this, cardToTopDeck);
            this.deck.AddCardToTop(cardToTopDeck);

            return cardToTopDeck;
        }

 private new void DoSpecializedCleanupAtStartOfCleanup(PlayerState currentPlayer, GameState gameState)
 {
     currentPlayer.RequestPlayerTopDeckCardFromPlay(gameState,
         acceptableCard => acceptableCard.isTreasure,
         isOptional: true);
 }