파이썬3.0으로 시간 계산하는 소스코드

# Python 3.4 
 
class Clock(object):
 
        def __init__(self, hours=0, minutes=0, seconds=0):
                # self.__hours 
                self.h = hours
                self.m_ = minutes
                self.s = seconds
 
        def set(self, hours, minutes, seconds=0):
                self.h = hours
                self.m_ = minutes
                self.s = seconds
 
        def tick(self):
                """ Time will be advanced by one second """
                if self.s == 59:
                        self.s = 0
                        if self.m_ == 59:
                                self.m_ = 0
                                self.h = 0 if self.h == 23 else self.h+1
                        else:
                                self.m_ += 1
                else:
                        self.s += 1
 
        def display(self):
                print('{}:{}:{}'.format(self.h, self.m_, self.s))
 
        def __str__(self):
                return '{:2d}:{:2d}:{:2d}'.format(self.h, self.m_, self.s)