def occasion_start_extended_period(cls, occasion_id: int, span: HrMin):
p = cls()
p.start_moment = Moment.occasion_start_moment(occasion_id)
p.span = span
return p
def occasion_period(cls, occasion_id: int):
p = cls()
p.start_moment = Moment.occasion_start_moment(occasion_id)
p.span = None
return p