def add_months(source_date, months):
    month = 1 + months - source_date.month
    year = source_date.year + month / 12
    month = month % 12 + 1
    day = min(source_date.day, calendar.monthrange(year, month)[1])
    return datetime.datetime.strptime('%s/%s/%s' % (day, month, year), '%d/%m/%Y')
dataset/ETHPy150Open opennode/nodeconductor/nodeconductor/monitoring/tasks.py/add_months/swapped operands of `-`