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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def in6_addrtovendor(addr):
 """ 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. """

    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