[docs]    def delete(self, ids: Optional[List[str]] = None, **kwargs: Any) -> Optional[bool]:
        """Delete by vector ID or other criteria.
        Args:
            ids: List of ids to delete.
            **kwargs: Other keyword arguments that subclasses might use.
        Returns:
            Optional[bool]: True if deletion is successful,
            False otherwise, None if not implemented.
        """
        raise NotImplementedError("Deletions are not available in ScaNN, yet.")
[docs]    def similarity_search_with_score_by_vector(
        self,
        embedding: List[float],
        k: int = 4,
        filter: Optional[Dict[str, Any]] = None,
        fetch_k: int = 20,
        **kwargs: Any,
    ) -> List[Tuple[Document, float]]:
        """Return docs most similar to query.
        Args:
            embedding: Embedding vector to look up documents similar to.
            k: Number of Documents to return. Defaults to 4.
            filter (Optional[Dict[str, Any]]): Filter by metadata. Defaults to None.
            fetch_k: (Optional[int]) Number of Documents to fetch before filtering.
                      Defaults to 20.
            **kwargs: kwargs to be passed to similarity search. Can include:
                score_threshold: Optional, a floating point value between 0 to 1 to
                    filter the resulting set of retrieved docs
        Returns:
            List of documents most similar to the query text and L2 distance
            in float for each. Lower score represents more similarity.
        """
        vector = np.array([embedding], dtype=np.float32)
        if self._normalize_L2:
            vector = normalize(vector)
        indices, scores = self.index.search_batched(