Tricky time representation in Python

slicetime.py

class SliceTime(object):
    @property
    def hour(self):
        return self._hour

    @hour.setter
    def hour(self, value):
        if not isinstance(value, (int, long)) or not 0 <= value <= 23:
            raise ValueError('hour must be an integer value in 0 ~ 23')
        else:
            self._hour = value

    @property
    def min(self):
        return self._min

    @min.setter
    def min(self, value):
        if not isinstance(value, (int, long)) or not 0 <= value <= 59:
            raise ValueError('min must be an integer value in 0 ~ 59')
        else:
            self._min = value

    @property
    def sec(self):
        return self._sec

    @sec.setter
    def sec(self, value):
        if not isinstance(value, (int, long)) or not 0 <= value <= 59:
            raise ValueError('sec must be an integer value in 0 ~ 59')
        else:
            self._sec = value

    def __repr__(self):
        return '<SliceTime {0.hour:02}:{0.min:02}:{0.sec:02}>'.format(self)

    def __getitem__(self, arg):
        if isinstance(arg, slice) and arg.start != None and arg.stop != None:
            self.hour = arg.start
            self.min = arg.stop
            self.sec = arg.step or 0
        elif isinstance(arg, (int, long)):
            self.hour = arg
            self.min = 0
            self.sec = 0
        else:
            raise Exception('invalid time format')

        return self

Time = SliceTime()

if __name__ == '__main__':
    print Time[12] # <SliceTime 12:00:00>
    print Time[15:30] # <SliceTime 15:30:00>
    print Time[5:45:20] # <SliceTime 05:45:20>