assert symbol.owner() == currentMember(): show(tree);
    private boolean location(Tree tree) {        Symbol symbol = tree.symbol();        assert symbol != null && symbol.isTerm(): show(tree);        assert !symbol.isMethod(): show(tree);        switch (tree) {        case Select(_, _):            return selection(tree);        case Ident(_):            if (symbol.isModule()) return true;            assert vvars.contains(symbol): show(tree);            assert symbol.owner() == currentMember(): show(tree);            return true;        default:            throw Debug.abort("illegal case", tree);        }    }