def months_ago(date, nb_months=1):
    """
    Return the given `date` with `nb_months` substracted from it.
    """
    nb_years = nb_months // 12
    nb_months = nb_months % 12
    month_diff = date.month - nb_months
    if month_diff > 0:
        new_month = month_diff
    else:
        new_month = 12 + month_diff
        nb_years += 1
    return date.replace(day=1, month=new_month, year=date.year - nb_years)
