ref: 0d7d70e5b1a4b5c7ae618d6d04fb30848b18c08f dir: /lib/std/swap.myr/
pkg std = generic swap : (a : @a#, b : @a# -> void) ;; generic swap = {a : @a#, b : @a# var t t = a# a# = b# b# = t }