public function setAutoFilter($filteredColumnName, $filteredValue)
    {
        if (!is_string($filteredColumnName)) {
            throw new InvalidArgumentException('setAutoFilter only accepts string as argument.');
        }
        if (!isset($filteredColumnName)) {
            throw new InvalidArgumentException('filteredValue must be set.');
        }
        $this->filteredColumnName = $filteredColumnName;
        $this->filteredValue = $filteredValue;
        return $this;
    }