'A :class:`datetime.datetime` instance representing the time of
generation for this :class:`ObjectId`.
The :class:`datetime.datetime` is timezone aware, and
represents the generation time in UTC. It is precise to the
second.'

@property
def generation_time(self):

    timestamp = struct.unpack('>i', self.__id[0:4])[0]
    return datetime.datetime.fromtimestamp(timestamp, utc)
