private Color verticalWinner() {
        for (int i = 0; i < board.length; i++) {
            Color current = Color.NONE;
            int length = 0;
            for (int j = 0; j < board[0].length; j++) {
                if (current == board[i][j]) {
                    length += 1;
                } else {
                    current = board[i][j];
                    length = 1;
                }
                if (length >= 4 && current.isNotNone()) {
                    return current;
                }
            }
        }
        return Color.NONE;
    }