Side note about the tests - a couple of compute tests randomly fail under Python 3.3 in trunk.

I think that is because some of the tests rely on the dictionary being ordered. This is generally a bad practice and won't work in Python 3.3 where hash randomization has been enabled by default (http://docs.python.org/3/whatsnew/3.3.html).

For now I commented some of those tests out, but it would be great if you could change them to not rely on the dictionary ordering.