import time


def time_strftime(fmt='%Y-%m-%d %H:%M:%S', ts=None, utc=False):
    return time.strftime(fmt, [time.localtime, time.gmtime][utc](ts))


def time_strptime(datetime_format='', dt=''):
    return time.mktime(time.strptime(dt, datetime_format))


if __name__ == '__main__':
    # Example.
    print(time_strftime(fmt='%Y年%m月%d日 %H:%M:%S'))
    print(time_strftime(fmt='%Y年%m月%d日 %H:%M:%S', ts=1640012345))
    print(time_strftime(fmt='%H:%M:%S', ts=120, utc=True))
    print(time_strptime('%Y-%m-%d %H:%M:%S', '2021-12-20 22:59:05'))