This was written in a matter of minutes.
The MAC address can be in most any format of between 6 and 12 digits -- even partial MAC addresses, as long as the first 6 digits are in there. Eg. aabb.ccdd.eeff, aa:bb:cc:dd:ee:ff, aa:bb:cc, aabb.c, aa:bb:cc:dd etc.
$ oui 88:e9:fe:xx:yy:zz
88:E9:FE Apple Apple, Inc.
Yeah, there's netaddr but their database source does not appear to be kept up to date. Wireshark really stays updated with their manuf file.