Copyright (c) 1983 Massachusetts Institute of Technology

	All rights reserved.  This software is distributed on the
	condition that any improvements or modifications to it are
	returned to the Scheme project at MIT.

	Permission to copy all or part of this material is granted,
	provided that the copies are not made or distributed for
	resale, the MIT copyright notice appears, and that notice is
	given that copying is by permission of Massachusetts Institute
	of Technology.