or set the TIMESCALE_SERVICE_URL environment variable.
        Example:
            .. code-block:: python
                from langchain.vectorstores import TimescaleVector
                from langchain.embeddings import OpenAIEmbeddings
                embeddings = OpenAIEmbeddings()
                text_embeddings = embeddings.embed_documents(texts)
                text_embedding_pairs = list(zip(texts, text_embeddings))
                tvs = TimescaleVector.from_embeddings(text_embedding_pairs, embeddings)
        """
        texts = [t[0] for t in text_embeddings]
        embeddings = [t[1] for t in text_embeddings]
        return await cls.__afrom(
            texts,
            embeddings,
            embedding,
            metadatas=metadatas,
            ids=ids,
            collection_name=collection_name,
            distance_strategy=distance_strategy,
            pre_delete_collection=pre_delete_collection,
            **kwargs,
        )
[docs]    @classmethod
    def from_existing_index(
        cls: Type[TimescaleVector],
        embedding: Embeddings,
        collection_name: str = _LANGCHAIN_DEFAULT_COLLECTION_NAME,
        distance_strategy: DistanceStrategy = DEFAULT_DISTANCE_STRATEGY,
        pre_delete_collection: bool = False,
        **kwargs: Any,
    ) -> TimescaleVector:
        """
        Get intsance of an existing TimescaleVector store.This method will
        return the instance of the store without inserting any new
        embeddings
        """
        service_url = cls.get_service_url(kwargs)
        store = cls(
            service_url=service_url,
            collection_name=collection_name,
            embedding=embedding,
            distance_strategy=distance_strategy,
            pre_delete_collection=pre_delete_collection,
        )
        return store
[docs]    @classmethod