public char winner() {
        String slots = "";
        for (int[] winComb : winCombs) {
            for (int aWinComb : winComb) slots += getSlot(aWinComb);
            if(slots.equals("XXXX") || slots.equals("XXX")) return slots.charAt(0);
            if(slots.equals("OOOO") || slots.equals("OOO")) return slots.charAt(0);
            slots = "";
        }
        return ' ';
    }