class Clock(object):
def __init__(self,hours=0, minutes=0, seconds=0):
self._hours = hours # protected, needed in ClockCalendar
self.__minutes = minutes
self.__seconds = seconds
def tick(self):
""" Time will be advanced by one second """
if self.__seconds == 59:
self.__seconds = 0
if self.__minutes == 59:
self.__minutes = 0
self._hours = 0 if self._hours==23 \
else self._hours + 1
else:
self.__minutes += 1
else:
self.__seconds += 1