ref: 98faed57da6da8b1e39ebaa2e9e4c22ac2cef5c3 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 }