Наследование: implements Everzet\PersistedObjects\Repository
 /** {@inheritdoc} */
 public function existsAlreadyGivenOfBook(UuidInterface $bookId)
 {
     /** @var Reservation $reservation */
     foreach ($this->file->getAll() as $reservation) {
         if ($reservation->bookId()->equals($bookId) && $reservation->isGivenAway()) {
             return true;
         }
     }
     return false;
 }
 public function add(User $user)
 {
     $this->file->save($user);
 }
 /** {@inheritdoc} */
 public function getAll()
 {
     return $this->file->getAll();
 }