def timestamp(self):
        "Return POSIX timestamp as float"
        if self._tzinfo is None:
            return _time.mktime((self.year, self.month, self.day,
                                 self.hour, self.minute, self.second,
                                 -1, -1, -1)) + self.microsecond / 1e6
        else:
            return (self - _EPOCH).total_seconds()
Return POSIX timestamp as float