code: public static function CHARACTER($character)
      {
          $character = Functions::flattenSingleValue($character);
  
          if ((!is_numeric($character)) || ($character < 0)) {
              return Functions::VALUE();
          }
  
          if (function_exists('iconv')) {
              return iconv('UCS-4LE', 'UTF-8', pack('V', $character));
          }
  
          return mb_convert_encoding('&#' . (int) $character . ';', 'UTF-8', 'HTML-ENTITIES');
      }
docs: CHARACTER.
  
  @param string $character Value
  
  @return string