Code examples are not included correctly.

At least in Chapter 19 (did not check the other chapters) most code examples are not included correctly. Instead there is a message box like ".. literalinclude:: src/chapter19/threadsafety.py"

I know it's been a while, but I ran into the same thing and I think I've got a pull request ( #20 ) to fix it. We'll have to wait and see if anyone merges it, though; this project looks slightly dead.