code: public static function HYPERLINK($linkURL = '', $displayName = null, Cell $pCell = null)
      {
          $linkURL = ($linkURL === null) ? '' : Functions::flattenSingleValue($linkURL);
          $displayName = ($displayName === null) ? '' : Functions::flattenSingleValue($displayName);
  
          if ((!is_object($pCell)) || (trim($linkURL) == '')) {
              return Functions::REF();
          }
  
          if ((is_object($displayName)) || trim($displayName) == '') {
              $displayName = $linkURL;
          }
  
          $pCell->getHyperlink()->setUrl($linkURL);
          $pCell->getHyperlink()->setTooltip($displayName);
  
          return $displayName;
      }
docs: HYPERLINK.
  
  Excel Function:
  =HYPERLINK(linkURL,displayName)
  
  @category Logical Functions
  
  @param string $linkURL Value to check, is also the value returned when no error
  @param string $displayName Value to return when testValue is an error condition
  @param Cell $pCell The cell to set the hyperlink in
  
  @return mixed The value of $displayName (or $linkURL if $displayName was blank)