This is the "handin" package for Racket, which provides infrastructure for automated handin and checking of programs from within DrRacket. Instructors use this infrastructure to generate a separate, course-specific ".plt" file (or package) that students install.
Install the "handin" package with
raco pkg install handin
or through the "Install Package..." menu item in DrRacket's "File" menu.
After installing, see the "Handin Server" documentation that is added to the Racket documentation.
Racket, including these packages, is free software, see LICENSE for more details.