// this syntax should be removed...
static O getThreadLocal(O o, S name) {
  ThreadLocal t = cast getOpt(o, name);
  ret t != null ? t.get() : null;
}

static <A> A getThreadLocal(ThreadLocal<A> tl) {
  ret tl == null ? null : tl!;
}

static <A> A getThreadLocal(ThreadLocal<A> tl, A defaultValue) {
  ret or(getThreadLocal(tl), defaultValue);
}