public function registerInterest($interest, $token)
    {
        if (! $this->isValidExpoPushToken($token)) {
            throw ExpoRegistrarException::invalidToken();
        }

        $stored = $this->repository->store($interest, $token);

        if (!$stored) {
            throw ExpoRegistrarException::couldNotRegisterInterest();
        }

        return $token;
    }