code: private function writeTitle(XMLWriter $objWriter, Title $title = null)
      {
          if ($title === null) {
              return;
          }
  
          $objWriter->startElement('c:title');
          $objWriter->startElement('c:tx');
          $objWriter->startElement('c:rich');
  
          $objWriter->startElement('a:bodyPr');
          $objWriter->endElement();
  
          $objWriter->startElement('a:lstStyle');
          $objWriter->endElement();
  
          $objWriter->startElement('a:p');
  
          $caption = $title->getCaption();
          if ((is_array($caption)) && (count($caption) > 0)) {
              $caption = $caption[0];
          }
          $this->getParentWriter()->getWriterPart('stringtable')->writeRichTextForCharts($objWriter, $caption, 'a');
  
          $objWriter->endElement();
          $objWriter->endElement();
          $objWriter->endElement();
  
          $this->writeLayout($objWriter, $title->getLayout());
  
          $objWriter->startElement('c:overlay');
          $objWriter->writeAttribute('val', 0);
          $objWriter->endElement();
  
          $objWriter->endElement();
      }
docs: Write Chart Title.
  
  @param XMLWriter $objWriter XML Writer
  @param Title $title
  
  @throws WriterException