Each of these examples is intended to replace the file user.c in the Kyu distribution. This is the intended way of adding your own code to Kyu. Of course once you understand the Makefile and the general way in which things are done, virtually anything is possible. This is however a good and recommended way to start.
If you simply download and build Kyu, this file will run the developer shell, which you can find documented somewhere. To try the examples in the tutorial, rename this and replace it with the tutorial, rebuild and run it.
Kyu / email@example.com