ref: 4e4f36fcf5177b0c51c4bcb5a203c5f86edf6e00 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 }