def store_hours(self, data):
        day_groups = []
        this_day_group = {}
        weekdays = ['Su', 'Mo', 'Th', 'We', 'Tu', 'Fr', 'Sa']
        for day_hour in data:
            if day_hour['idx'] > 7:
                continue

            hours = ''
            start, end = day_hour['value'].split("-")[0].strip(), day_hour['value'].split("-")[1].strip()

            short_day = weekdays[day_hour['idx'] - 1]
            hours = '{}:{}-{}:{}'.format(start[:2], start[3:], end[:2], end[3:])
            if not this_day_group:
                this_day_group = {
                    'from_day': short_day,
                    'to_day': short_day,
                    'hours': hours,
                }

            elif hours == this_day_group['hours']:
                this_day_group['to_day'] = short_day

            elif hours != this_day_group['hours']:
                day_groups.append(this_day_group)
                this_day_group = {
                    'from_day': short_day,
                    'to_day': short_day,
                    'hours': hours,
                }

        day_groups.append(this_day_group)

        if not day_groups:
            return None
        opening_hours = ''
        if len(day_groups) == 1 and not day_groups[0]:
            return None
        if len(day_groups) == 1 and day_groups[0]['hours'] in ('00:00-23:59', '00:00-00:00'):
            opening_hours = '24/7'
        else:
            for day_group in day_groups:
                if day_group['from_day'] == day_group['to_day']:
                    opening_hours += '{from_day} {hours}; '.format(**day_group)
                else:
                    opening_hours += '{from_day}-{to_day} {hours}; '.format(**day_group)
            opening_hours = opening_hours [:-2]

        return opening_hours