public function isFullyEvaluated(Paper $paper)
    {
        return 0 === (int) $this->getEntityManager()
            ->createQuery('
                SELECT COUNT(a)
                FROM UJM\ExoBundle\Entity\Attempt\Answer AS a
                WHERE a.paper = :paper
                  AND a.score IS NULL
            ')
            ->setParameters([
                'paper' => $paper,
            ])
            ->getSingleScalarResult();
    }