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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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)