private static Move ForwardLeftForBlack(int r, int c, Board board){
        Move forwardLeft = null;
        
        assert(board.cell[r][c] == CellEntry.black || board.cell[r][c] == CellEntry.blackKing);
        
        if( r>=1 && c<Board.cols-1 &&
                board.cell[r-1][c+1] == CellEntry.empty
                
          )
        {
            forwardLeft = new Move(r,c,r-1, c+1);
        }
        return forwardLeft;
    }