Plan 9 from Bell Labs’s /usr/web/sources/patch/maybe/ape-updates/nap.c
extern int _SLEEP(long); /* * from nap(2), 8th edition. assume 60Hz * won't overflow. n can be no bigger than 2*60. * * obsolete. */ int nap(int n) { _SLEEP((n*16667)/1000); return 0; }