root.map(Activation::getOs).ifPresent(oa -> {
            stk.push(new ActivationFrame("os", Optional.of(oa)));
            stk.push(new ActivationFrame("arch", Optional.empty()));
            validator.accept(oa.getArch());
            stk.peek().location = "family";
            validator.accept(oa.getFamily());
            stk.peek().location = "name";
            validator.accept(oa.getName());

// result against a golden file.

func testEndToEnd(t *testing.T, goarch, file string) {
	input := filepath.Join("testdata", file+".s")
	architecture, ctxt := setArch(goarch)
	architecture.Init(ctxt)
	lexer := lex.NewLexer(input)
	parser := NewParser(ctxt, architecture, lexer)
	pList := new(obj.Plist)
	var ok bool