In `clone.c`:

```
        // object._xopEquals
        Identifier *id = Lexer::idPool("_xopEquals");
        Expression *e = new IdentifierExp(loc, Id::empty);
        e = new DotIdExp(loc, e, Id::object);
        e = new DotIdExp(loc, e, id);
```

Similarly to:

```
    TypeIdentifier *tid = new TypeIdentifier(Loc(), Id::empty);
    tid->addIdent(Id::object);
    tid->addIdent(Id::Throwable);
    type = tid;
```