public function copy(Exercise $exercise)
    {
        // Serialize quiz entities
        $exerciseData = $this->serializer->serialize($exercise, [Transfer::INCLUDE_SOLUTIONS]);

        // Populate new entities with original data
        $newExercise = $this->createCopy($exerciseData, null);

        // Save copy to db
        $this->om->flush();

        return $newExercise;
    }