// returns minimal time needed (nanos)
static long benchFor5Seconds(S desc, Runnable r) {
  ret benchForNSeconds(desc, r, 5);
}

static long benchFor5Seconds(Runnable r) {
  ret benchFor5Seconds(str(r), r);
}

// returns result of function
static <A> A benchFor5Seconds(S desc default str(f), IF0<A> f) {
  benchFor5Seconds(desc, r { f! });
  ret f!;
}