Hm. I get paid to write in what I write in. Subtle difference. ;)
I truly appreciated the power of anonymity in dynamic languages today, when I wrote:
categories = {}.fromkeys(categories).keys()
which removes duplicate items from the sequence named 'categories'. The {} creates a new, anonymous dictionary, which is first populated with .fromkeys(), then immediately consumed by .keys(), which returns the list I want.
Of course, if I did this regularly, I would put it in a named function, like 'flatten' or 'dedupe' or something. But you get the idea.