ref: 4e656a4f039b9230c820f12d3b1e4a5c8e55cf47 dir: /libstd/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 }