from time import sleep

class Clock(object):
"""数字时钟"""

def __init__(self, hour=0, minute=0, second=0):
"""初始化方法

:param hour: 时
:param minute: 分
:param second: 秒
"""
self._hour = hour
self._minute = minute
self._second = second

def run(self):
"""走字"""
self._second += 1
if self._second == 60:
self._second = 0
self._minute += 1
if self._minute == 60:
self._minute = 0
self._hour += 1
if self._hour == 24:
self._hour = 0

def show(self):
"""显示时间"""
return '%02d:%02d:%02d' % \
(self._hour, self._minute, self._second)

def main():
clock = Clock(23, 59, 58)
while True:
print(clock.show())
sleep(1)
clock.run()

if __name__ == '__main__':
main()