generates a UUID for a given datetime

        :param dt: datetime
        :type dt: datetime
        :return:

def from_datetime(self, dt):
        """
        generates a UUID for a given datetime

        :param dt: datetime
        :type dt: datetime
        :return:
        """
        global _last_timestamp

        epoch = datetime(1970, 1, 1, tzinfo=dt.tzinfo)
        offset = epoch.tzinfo.utcoffset(epoch).total_seconds() if epoch.tzinfo else 0
        timestamp = (dt  - epoch).total_seconds() - offset

        node = None
        clock_seq = None

        nanoseconds = int(timestamp * 1e9)
        timestamp = int(nanoseconds // 100) + 0x01b21dd213814000

        if clock_seq is None:
            import random
            clock_seq = random.randrange(1 << 14)  # instead of stable storage
        time_low = timestamp & 0xffffffff
        time_mid = (timestamp >> 32) & 0xffff
        time_hi_version = (timestamp >> 48) & 0x0fff
        clock_seq_low = clock_seq & 0xff
        clock_seq_hi_variant = (clock_seq >> 8) & 0x3f
        if node is None:
            node = getnode()
        return pyUUID(fields=(time_low, time_mid, time_hi_version,
                            clock_seq_hi_variant, clock_seq_low, node), version=1)