public function clearCellsFormatting($startRow, $startColumn, $endRow, $endColumn)
    {
        if ($startRow == '')
            throw new Exception('Start Row not specified');
        
        if ($startColumn == '')
            throw new Exception('Start Column not specified');
        
        if ($endRow == '')
            throw new Exception('End Row not specified');
        
        if ($endColumn == '')
            throw new Exception('End Column not specified');
        
        //Build URI
        $strURI = Product::$baseProductUri . '/cells/' . $this->getFileName() . '/worksheets/' . $this->worksheetName . 
                  '/cells/ClearFormats?startRow=' . $startRow . '&startColumn=' . $startColumn . 
                  '&endRow=' . $endRow . '&endColumn=' . $endColumn;
        //Sign URI
        $signedURI = Utils::sign($strURI);
        
        //Send request and receive response stream
        $responseStream = Utils::processCommand($signedURI, 'POST', '', '');
        
        $v_output = Utils::validateOutput($responseStream);
        
        if ($v_output == '') {
            $strURI = Product::$baseProductUri . '/storage/file/' . $this->getFileName();
            $signedURI = Utils::Sign($strURI);
            $responseStream = Utils::processCommand($signedURI, "GET", "", "");

            $outputPath = AsposeApp::$outPutLocation . $this->getFileName();
            Utils::saveFile($responseStream, $outputPath);
            return $outputPath;
        }    
        else
            return $v_output;
    }