ref: b37fc330005640f45c9691fe256993cb0b4e3e6c dir: /lib/thread/ncpu+plan9.myr/
use std pkg thread = const ncpu : (-> int) ;; const ncpu = { match std.intparse(std.getenvv("NPROC", "")) | `std.Some n: -> n | `std.None: -> 1 ;; }