Changes by: Jason Hickey (jyh at cs.caltech.edu)
Date: 2005-02-03 21:29:29 -0800 (Thu, 03 Feb 2005)
Revision: 6592
Log message:
Prevent redeclaration of shapes.
Note that Itt_rat, Itt_rbtree had errors in this respect,
using define more than once on the same shape.