Returns a time that n seconds after a time.

    :param datetimestr: a datetime object or a datetime str
    :param n: number of seconds, value can be negative

    **中文文档**

    返回给定日期N秒之后的时间。

def add_seconds(datetime_like_object, n, return_date=False):
    """
    Returns a time that n seconds after a time.

    :param datetimestr: a datetime object or a datetime str
    :param n: number of seconds, value can be negative

    **中文文档**

    返回给定日期N秒之后的时间。
    """
    a_datetime = parser.parse_datetime(datetime_like_object)
    a_datetime = a_datetime + timedelta(seconds=n)
    if return_date:  # pragma: no cover
        return a_datetime.date()
    else:
        return a_datetime