update comment
ex 5.9 - done
simu - plan to verify impl
ex 5.2 - split controller code
ex 5.2 - use simu
simu - bug fix qq
simu - execute with reg-bindings, turn off tests
legacy simu - pop should be made procedure
legacy simu - now it works at least for ex 5.2
legacy simu - "legacy-easy"
simu - few controller-text to insns
ex 5.3 - move controller
ex 5.2 - fix - don't need to drop car
simu - more primitives
ex 5.3 - simu version
ex 5.3 - legacy version
simu legacy - make primitive list an option
ex 5.3 - use concat
ex 5.3 - both simu and legacy are now tested
ex 5.4 - simu passed