private static function getFeedItemIdsFromArgument($function)
    {
        $feedItemIds = [];

        if (count($function->getLhsOperand()) === 1
            && $function->getLhsOperand()[0] instanceof RequestContextOperand
            && $function->getLhsOperand()[0]->getContextType() === RequestContextOperandContextType::FEED_ITEM_ID
            && $function->getOperator() === FunctionOperator::IN) {
            foreach ($function->getRhsOperand() as $argument) {
                $feedItemIds[] = $argument->getLongValue();
            }
        }

        return $feedItemIds;
    }