Medusa\Queue\PersistentQueue::dequeue PHP Метод

    public function dequeue()
    {
        $f = $this->forwards->pop();
        if ($f->isEmpty() && $this->backwards->isEmpty()) {
            return self::createEmpty();
        }
        if ($f->isEmpty()) {
            return new self($this->reversedBackwards(), PersistentStack::createEmpty(), $this->count - 1);
        }
        return new self($f, $this->backwards, $this->count - 1);
    }