public function getWorkingHours($specialist, $branch, $from, $to) {
        $query = $this->calendarQueryFactory->create()
            ->byDateInterval($from, $to)
            ->byUser($specialist->id)
            ->byBranch($branch->id)
            ->byTemplate([
                EventTemplate::APPOINTMENT_VSK,
                EventTemplate::APPOINTMENT_KNT,
                EventTemplate::APPOINTMENT_CHECKUP,
                EventTemplate::APPOINTMENT_FREE,
            ]);

        $events = $this->em->getRepository(Entities\Event::class)->fetch($query);

        $workingHours = 0;

        foreach ($events as $event) {
            $hourDiff = $event->start->diff($event->end, TRUE)->format('%h');
            $workingHours += $hourDiff;
        }

        return $workingHours;
    }