This tiny piece of software improves the reliability and maintainability of your code. Like most of the dials and gauges in a Boeing 747 cockpit are for monitoring performance (rather than actually flying the plane), this library allows to you to have your program monitor itself, and report its state. If you aren't familiar with this idea, read 'Writing Solid Code' (Microsoft Press). You should also be aware of the C standard library function assert (<assert.h>).