This is probably too little to justify the compatibility breakage, but is there a motive for the "slice" type to be on built-ins ? (besides people forgot it there at PEP-3000 time?) It is normally used in super-specialized cases, mostly when one is implementing a Sequence type, and even there just for type-checking, not to create new slice objects. It seems to me it should lie on the "types" module (or some other place), rather than eat built-in namespace (which can confuse newcomers anyway). As I said, the benefits of moving it to a less prominent place may be to little, and incompatibilities would ensue since all modules using it don't expect to have to import it anyway. But maybe thsi should be a thing to keep an eye on for some future Python release? js -><-