Instagram/python-instagram — pull request #16 by michaelhelmick (2012-02-24 18:49:03+00:00)
Title: Default args should not be mutable

I can't find the exact blog that I learned it on, but this should be a
good enough explaination:

http://www.itmaybeahack.com/book/python-2.6/html/p02/p02c05_maps.html#us
ing-dictionaries-as-function-parameter-defaults