# def custom_export(players):
#     # header row
#     yield ['session', 'participant_code', 'round_number', 'id_in_group', 'ritoku','period','is_infected']
#     for p in players:
#         yield [p.session.code, p.participant.code, p.round_number, p.id_in_group, p.ritoku, p.period, p.is_infected]