8.1 Simplest example

As a nice simple, indeed trivial example consider the following:

1. Include `nana.h' in your project wide include file.
2. Use `I' to check invariants in your code. In particular all functions or methods should be required to check their pre and post conditions.
3. Use `DL' to print debugging messages in your code. This means that debugging messages only occur when you run the program under the debugger.¹