protected function makePickle(\Plop\RecordInterface $record)
    {
        // To maintain full compatibility with Python,
        // we should emulate pickle here, but it seems
        // to be quite some work and PHP already has
        // it's own serialization mechanism anyway.
        $s      = serialize($record);
        $slen   = pack('N', strlen($s));
        return $slen.$s;
    }