[$] Python data classes

The reminder that the feature freeze forPython 3.7 is coming up fairly soon (January 29) was met with aflurry of activity on the python-dev mailing list. Numerous Pythonenhancement proposals (PEPs) were updated or newly proposed; other featuresor changes have been discussed as well. One of the updated PEPs is proposing anew type of class, a"data class", to be added to the standard library. Data classes wouldserve much the same purpose as structures or records in other languages andwould use the relatively new type annotationsfeature to support static type checking of the use of the classes.