python-crontab表达式

起源于一个比较奇葩的需求，默认的celery无法实现：

需要用户输入一个开始时间，结束时间，以及时间间隔，需要在该时间段内指定间隔执行

import datetime


def task(start: datetime.datetime, end: datetime.datetime, interval: datetime.timedelta):
    """
    * * * * *
    """
    time_list = []
    result_dict = {}
    today = datetime.datetime.now()
    current = start
    while current < end:
        current_time = current.time()
        time_list.append(current_time)
        current += interval
    for i in time_list:
        if i.hour not in result_dict:
            result_dict[i.hour] = []
        result_dict[i.hour].append(i)
    for k, v in result_dict.items():
        m_list = []
        for j in v:
            m_list.append(str(j.minute))
        print(f"{','.join(m_list)} {k} {today.day} {today.month} *")


if __name__ == '__main__':
    time2 = "15:16:08"
    time4 = "18:16:08"
    start_time = datetime.datetime.strptime(time2, "%H:%M:%S")
    end_time = datetime.datetime.strptime(time4, "%H:%M:%S")
    task(start_time, end_time, datetime.timedelta(seconds=420))