private function updateMaxColumn($currentColumn)
    {
        $max = $this->maxColumn;

        if (strlen($currentColumn) > strlen($max)) {
            return $this->maxColumn = $currentColumn;
        } elseif (strlen($currentColumn) < strlen($max)) {
            // do nothing
        } elseif (strlen($currentColumn) == 1 && strlen($max) == 1) {
            if ($currentColumn > $max) {
                $this->maxColumn = $currentColumn;
            }
        } elseif ($currentColumn[0] > $max[0]) {
            $this->maxColumn = $currentColumn;
        } elseif (($currentColumn[0] == $max[0]) && $currentColumn[1] > $max[1]) {
            $this->maxColumn = $currentColumn;
        }

        return true;
    }