In cases where it makes sense to do explicit type checking (with ABCs or whatever), I really detest the look of the isinstance() function. if isinstance(thing, Fruit) and not isinstance(thing, Apple): Yucky. What I really want to write is: if thing is a Fruit and thing is not an Apple: and after thinking about it on and off for a while I wonder if it might indeed be possible to teach the parser to handle that in a way that eliminates almost all possible ambiguity with the regular "is", including perhaps 100% of all existing standard library code and almost all user code? Maybe this has been considered at some point in the past? The "is [not] a|an" proposal would at least be a strong contender for "hardest thing to search for on the internet" lol. Thanks! Gavin