code: public static function chr($ord, $encoding = 'UTF-8')
      {
          if ($ord <= 255) {
              return chr($ord);
          }
          if ($encoding === 'UCS-4BE') {
              return pack('N', $ord);
          }
  
          return mb_convert_encoding(self::chr($ord, 'UCS-4BE'), $encoding, 'UCS-4BE');
      }
docs: UTF-8 compatible chr()
  
  @param string $ord
  @param string $encoding
  
  @return string