public function spop($key, $count = 1)
    {
        $this->init();
        if ($count == 1 || $count === null) {
            $result = $this->driver->spop($key);
            return $this->convertFalseToNull($result);
        }

        $members = [];
        for ($i = 0; $i < $count; ++$i) {
            $member = $this->driver->spop($key);
            if (!$member) {
                break;
            }
            $members[] = $member;
        }
        return empty($members) ? null : $members;
    }