'Return the matched vendor name for the given MAC address
or Unknown if no match is found
:param self: A MACMatcher object
:param mac_address: MAC address of device
:type self: MACMatcher
:type mac_address: string
:return: The vendor name of the device if MAC address is found
and Unknown otherwise
:rtype: string'

def get_vendor_name(self, mac_address):

    if (mac_address is None):
        return None
    mac_identifier = mac_address.replace(':', '').upper()[0:6]
    try:
        vendor = self._mac_to_vendor[mac_identifier][0]
        return vendor
    except KeyError:
        return 'Unknown'
