code: public function listWorksheetNames($pFilename)
      {
          File::assertFile($pFilename);
          if (!$this->canRead($pFilename)) {
              throw new Exception($pFilename . ' is an Invalid Spreadsheet file.');
          }
  
          $worksheetNames = [];
  
          $xml = $this->trySimpleXMLLoadString($pFilename);
  
          $namespaces = $xml->getNamespaces(true);
  
          $xml_ss = $xml->children($namespaces['ss']);
          foreach ($xml_ss->Worksheet as $worksheet) {
              $worksheet_ss = $worksheet->attributes($namespaces['ss']);
              $worksheetNames[] = self::convertStringEncoding((string) $worksheet_ss['Name'], $this->charSet);
          }
  
          return $worksheetNames;
      }
docs: Reads names of the worksheets from a file, without parsing the whole file to a Spreadsheet object.
  
  @param string $pFilename
  
  @throws Exception
  
  @return array