Of course, I'm for it. But we have to be consistent... I was surprised to realize `complex` doesn't accept '2 + 3j' (even though it accepts '(2+3j)', and even '\n2+3j\t'). There are a lot of slippery slopes here (e.g. how about 3_j?). I think that once we allowed _ in integer literals, suddenly we could add more separation between digits than around them in many contexts, and that just seems wrong.