Brett Cannon email@example.com added the comment:
I'm not questioning if people have ever created a base exception for an entire package, I'm just asking how often it's actually used when the base exception didn't make sense outside of the rule-of-thumb Nathaniel is pointing out?
For instance, it could makes sense in requests' case to have a base exception to help facilitate catching network-related errors but let through e.g. TypeError. But does that extend to most packages such that users regularly write an 'except' clause catching that package's common base exception type? That's my question and I personally don't have an answer beyond reflecting on this and not really remembering a case where I have (I _can_ remember following this pattern simply because it's habit at this point for some unknown reason :) .