Over the last few days, I have been spending some time working on my python - reading the sections of Diving into Python that I have never got around to and refactoring parts of some of my python scripts to make better use of the features of language and, ultimately, to make them more robust (i.e. usable by people other than me). The script I have started with is a simple one for registering hosts for DHCP access. Basically, it takes two command line arguments - a fully qualified hostname and a MAC address - and then does some validation, checks that neither address is already in use, normalizes the output to the correct format, constructs a properly formatted host stanza and appends it to the end of our ISC DHCP servers dhcpd.conf configuration file. I have made improvements to various parts of the code but the changes I am most conflicted about are those I have made to the MAC address normalization function which works reliably and therefore probably isn't a good candidate for