ref: 02fa3c02b2bf6f5b7e8473fcb3d8e0140ce9c17e 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 }