updates
the difference

diff -u <(git cat-file -p a95b096) sicp8.rkt > sicp7-8.rkt.diff
copy to continue on
prepare to apply patch
part of patch that applied cleanly
manually ported changes
fix typo :)
remove duplicate code (that removes the =zero? etc., and/or misses type bug fix)
open question
fix: aha that was not actually a bug!

introduced in 4548dbd8fb1838b952fd2129a1c479372ae3ef23
.