return self.override_relevance_score_fn
        # Default strategy is to rely on distance strategy provided in
        # vectorstore constructor
        if self.distance_strategy == DistanceStrategy.MAX_INNER_PRODUCT:
            return self._max_inner_product_relevance_score_fn
        elif self.distance_strategy == DistanceStrategy.EUCLIDEAN_DISTANCE:
            # Default behavior is to use euclidean distance relevancy
            return self._euclidean_relevance_score_fn
        else:
            raise ValueError(
                "Unknown distance strategy, must be cosine, max_inner_product,"
                " or euclidean"
            )
    def _similarity_search_with_relevance_scores(
        self,
        query: str,
        k: int = 4,
        filter: Optional[Dict[str, Any]] = None,
        fetch_k: int = 20,
        **kwargs: Any,
    ) -> List[Tuple[Document, float]]:
        """Return docs and their similarity scores on a scale from 0 to 1."""
        # Pop score threshold so that only relevancy scores, not raw scores, are
        # filtered.
        score_threshold = kwargs.pop("score_threshold", None)
        relevance_score_fn = self._select_relevance_score_fn()
        if relevance_score_fn is None:
            raise ValueError(
                "normalize_score_fn must be provided to"
                " ScaNN constructor to normalize scores"
            )
        docs_and_scores = self.similarity_search_with_score(
            query,
            k=k,
            filter=filter,
            fetch_k=fetch_k,
            **kwargs,
        )
        docs_and_rel_scores = [
            (doc, relevance_score_fn(score)) for doc, score in docs_and_scores
        ]
        if score_threshold is not None: