ref: 41dfa1df58c7e398a68e9c2b6f6f745b7b3f0b2b 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 }