public function getSheet($pIndex)
    {
        if (!isset($this->workSheetCollection[$pIndex])) {
            $numSheets = $this->getSheetCount();

            throw new Exception(
                "Your requested sheet index: {$pIndex} is out of bounds. The actual number of sheets is {$numSheets}."
            );
        }

        return $this->workSheetCollection[$pIndex];
    }