Handles tracking and cleanup of custom ids.

def id(self, opts_id):
        """Handles tracking and cleanup of custom ids."""
        old_id = self._id
        self._id = opts_id
        if old_id is not None:
            cleanup_custom_options(old_id)
        if opts_id is not None and opts_id != old_id:
            if opts_id not in Store._weakrefs:
                Store._weakrefs[opts_id] = []
            ref = weakref.ref(self, partial(cleanup_custom_options, opts_id))
            Store._weakrefs[opts_id].append(ref)