public string GetPrevMoveEran()
        {
            if (Plies <= FirstPly)
            {
                return(null);
            }

            var e = BoardHistory.Prev();

            if (e == null)
            {
                return(null);
            }

            var move = BoardHistory.Current().Move;

            if (move == null)
            {
                return(null);
            }

            return(Eran.MakeFromBoardAndMove(
                       new ChessGame(e.GCD),
                       move
                       ));
        }
 public string GetPrevFen()
 {
     return(BoardHistory.Prev().GetFen());
 }