We're back after a server migration that caused effbot.org to fall over a bit harder than expected. Expect some glitches.

The __nonzero__ method


Called to implement truth value testing, and the built-in operation bool; should return False or True, or their integer equivalents 0 or 1. When this method is not defined, __len__ is called, if it is defined. If a class defines neither __len__ nor __nonzero__, all its instances are considered true.