Presenters can be a comma-separated list of presenters.

def create_journal_club_meeting(self, presenters, food_vendor, paper = None):
        'Presenters can be a comma-separated list of presenters.'
        e = self.initialize_tagged_copy()
        e['extendedProperties']['shared']['event_type'] = 'Journal club'
        e['extendedProperties']['shared']['Presenters'] = presenters
        e['extendedProperties']['shared']['Food vendor'] = food_vendor
        e['extendedProperties']['shared']['Paper'] = paper
        participants = [p.strip() for p in [p for p in presenters.split(',')] if p and p.strip()]
        participants = [p for p in [self.email_map.get(p) for p in participants] if p]
        participant_names = [self.username_map.get(p.strip(), p.strip()) for p in presenters.split(',') if p.strip()]
        if participants:
            e['extendedProperties']['shared']['ParticipantList'] = ','.join(participants)
        if not e['summary']:
            e['summary'] = 'Journal club: %s' % (', '.join(participant_names))
        e['description'] = e['description'] or e['summary']
        return e