ref: 21b5fb876c5f1e6188a3a6b0e9e77311f06525f0 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 }