Sorry I see there was misunderstanding.  All I mean was to subclass your specific exceptions off of something that already exists instead of the generic <code>Exception</code> class.  It doesn't have to be a <code>error.TestError</code>, you could use <code>TypeError, AttributeError, etc.</code> or something like that too.  Anyway, it was just advice from a video I watched recently, "Stop Making New Classes".  The point was to re-use existing standard-library exceptions as much as possible because it's simpler to understand then making everything custom.  Either way, it's just advice/suggestion, if you think it won't work, then no prob.