def get_time(start_time, end_time):
    """
    transfer time type
    :param start_time: "20181218"
    :param end_time: "20181220"
    :return: "2018-12-18 00:00:01", "2018-12-20 23:59:59"
    """
    res1, res2 = "00:00:01", "23:59:59"
    start_time, end_time = str(start_time), str(end_time)
    time1 = "-".join([start_time[:4], start_time[4:6], start_time[6:]])
    time2 = "-".join([end_time[:4], end_time[4:6], end_time[6:]])
    return " ".join([time1, res1]), " ".join([time2, res2])