def _add_reranker(self, reranker: lancedb.rerankers.Reranker) -> None:
        """Add a reranker to an existing vector store."""
        if reranker is None:
            raise ValueError(
                "`reranker` has to be a lancedb.rerankers.Reranker object."
            )
        self._reranker = reranker
Add a reranker to an existing vector store.
llama-index-integrations/vector_stores/llama-index-vector-stores-lancedb/llama_index/vector_stores/lancedb/base.py