Why is it a mess?

Yeah. But even python considers boolean false and integer zero to be equivalent, and all other integers to be true. Indeed the method to override to define your own behaviour for if object is object.__nonzero__ or object.__len__

From the naming alone it's clear that being "true" by convention means "having length" or "not being zero". (why is the method __nonzero__ and not __zero__ (with opposite semantics) by the way, seems an odd kind of superfluous negation. Returning false hear means that the object is *not* *nonzero* i.e. that it's zero.