ref: 515b8e89c1a6c0859eaefbf7835a4e6497a57e0b 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 }