void placePiece(Space space, Piece piece) {
		if (!space.isValid()) {
			invalidMove = true;
		} else if (space.getPiece() == N) {
			space.setPiece(piece);
			invalidMove = false;
		} else {
			invalidMove = true;
		}
		if (!invalidMove) {
			lastSpaceMoved = space;
			if (piece == X)
				lastXMoved = lastSpaceMoved;
			else
				lastOMoved = lastSpaceMoved;
		}
		if (userWon())
			isDone = true;
		if(user2Won())
			isDone = true;
		if(getOpenSpaces().length==0)
			isDone = true;
	}