ref: 2c27f80bb5f4d8084f1d8cf9d01c4377dba92c2f 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 }