in Server/php/app_token_options.php [17:35]
public function pack(): string
{
$buf = '';
if ($this->engine_options === null) {
$buf .= pack('C', 0);
} else {
$buf .= pack('C', 1);
$buf .= pack('N', count($this->engine_options));
ksort($this->engine_options);
foreach ($this->engine_options as $key => $value) {
if ($key === null || $value === null) {
throw new \ValueError('illegal engineOptions entry');
}
$buf .= pack('N', strlen($key)) . $key;
$buf .= pack('N', strlen($value)) . $value;
}
}
return $buf;
}