Foreman-Mackey returned from his furlough at Queens, where he was finishing a paper with Widrow on Andromeda. I quizzed him about some details of cacheing (very slow computations) in my Python RGB-to-CMYK code; he had good ideas. One thing he noted that instead of doing if rgb in cache.keys(): it might be far faster to do try: cmyk = cache[rgb] and then catch the KeyError exception. Apparently that is the rage and style in Python programming. He also promised to help me Python-package and docstring everything. Looking forward to it!
[Note added a few minutes later: Switching from the keys() check to the try style sped up the cache retrieval by a factor of 40!]