args.sh - using if, $#, 1>&2

PI.cc - C++ has constexpr keyword, PI.s shows pi read-only: .section .rodata

badpi.c - attempt to change read-only data -> crash

pi.c, g.c - using volatile const

union examples: search for union in ss spreadsheet source code
 at http://fog.misty.com/perry/ss/src/ss.h
also see traverse example: http://fog.misty.com/perry/osp/ll/traverse.gif