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.