Mutual module imports

[Tuvas]

The trick is via something called Extending. Pyrex just makes extending
a bit easier, but, depending on the complexity of the function, it
might be easier just to extend it yourself. Basically you make a
function that translates python into C. There are some instructions on
the Python website, http://www.python.org . Look around, and you'll
find lots of cool stuff on it.