/**
* User must be the owner of lesson exercise belongs to.
*
* @param User $user
* @param Exercise $exercise
* @return bool
*/
public function modify(User $user, Exercise $exercise) : bool
{
return User::query()->join('lessons', 'lessons.owner_id', '=', 'users.id')->join('exercises', 'exercises.lesson_id', '=', 'lessons.id')->where('exercises.id', '=', $exercise->id)->where('users.id', '=', $user->id)->exists();
}
