python 獲取上個月第一天和最后一天

# 獲取上個月第一天和最后一天
def get_last_month_first_last_day(date_param: datetime):
    """
    :param date_param:  接受一個日期參數 datetime類型
    :return:  返回上個月第一天和最后一天
    """
    if not isinstance(date_param, datetime.datetime):
        raise TypeError("Please pass the <class 'datetime.datetime'>")
    m_last_day = datetime.date(date_param.year, date_param.month, 1) - datetime.timedelta(days=1)
    m_first_day = datetime.date(m_last_day.year, m_last_day.month, 1)
    return m_first_day, m_last_day