code: def in6_addrtovendor(addr):
      
      mac = in6_addrtomac(addr)
      if mac is None or conf.manufdb is None:
          return None
  
      res = conf.manufdb._get_manuf(mac)
      if len(res) == 17 and res.count(':') != 5:  # Mac address, i.e. unknown
          res = "UNKNOWN"
  
      return res
docs: Extract the MAC address from a modified EUI-64 constructed IPv6
      address provided and use the IANA oui.txt file to get the vendor.
      The database used for the conversion is the one loaded by Scapy
      from a Wireshark installation if discovered in a well-known
      location. None is returned on error, "UNKNOWN" if the vendor is
      unknown.