This component of Racket is distributed under the under the Apache 2.0
and MIT licenses. The user can choose the license under which they
will be using the software. There may be other licenses within the
distribution with which the user must also comply.

See the files
  https://github.com/racket/racket/blob/master/racket/src/LICENSE-APACHE.txt
and
  https://github.com/racket/racket/blob/master/racket/src/LICENSE-MIT.txt
for the full text of the licenses.