public function getCalendarsForRoute($externalCoverageId, $externalRouteId, \DateTime $startDate, \DateTime $endDate)
    {
        $calendarsData = $this->navitia->getRouteCalendars($externalCoverageId, $externalRouteId, $startDate, $endDate);
        $calendarsSorted = array();
        if (isset($calendarsData->calendars) && !empty($calendarsData->calendars)) {
            foreach ($calendarsData->calendars as $calendar) {
                //make it easier for template
                $calendarsSorted[$calendar->id] = $calendar;
            }
        }

        return $calendarsSorted;
    }