ref: 0c0a9801c0e2b92832a9f91d6a6e7f94e8ba277d 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 }