code: private function utf8Encode($s)
      {
          $s .= $s;
          $len = \strlen($s);
          for ($i = $len >> 1, $j = 0; $i < $len; ++$i, ++$j) {
              switch (true) {
                  case $s[$i] < "\x80": $s[$j] = $s[$i]; break;
                  case $s[$i] < "\xC0": $s[$j] = "\xC2"; $s[++$j] = $s[$i]; break;
                  default: $s[$j] = "\xC3"; $s[++$j] = \chr(\ord($s[$i]) - 64); break;
              }
          }
          return substr($s, 0, $j);
      }
docs: Encodes an ISO-8859-1 string to UTF-8
  @param string $s
  @return string the UTF-8 translation of `s`.
  @see https://github.com/symfony/polyfill-php72/blob/master/Php72.php#L24