code: def teredo(self):
          
          if (self._ip >> 96) != 0x20010000:
              return None
          return (IPv4Address((self._ip >> 64) & 0xFFFFFFFF),
                  IPv4Address(~self._ip & 0xFFFFFFFF))
docs: Tuple of embedded teredo IPs.
  
          Returns:
              Tuple of the (server, client) IPs or None if the address
              doesn't appear to be a teredo address (doesn't start with
              2001::/32)