private static void appendPiece(Board board, StringBuilder s, int r, int c) {
		switch (board.getCell(r, c)) {
			case BLACK_PIECE : s.append('x'); break;
			case BLACK_QUEEN : s.append('X'); break;
			case WHITE_QUEEN : s.append('Q'); break;
			case WHITE_PIECE : s.append('o'); break;
		}
	}