langchain/vectorstores/pinecone.py/Pinecone/from_existing_index
class Pinecone:    def from_existing_index(
        cls,
        index_name: str,
        embedding: Embeddings,
        text_key: str = "text",
        namespace: Optional[str] = None,
    ) -> Pinecone:
        """Load pinecone vectorstore from index name."""
        try:
            import pinecone
        except ImportError:
            raise ValueError(
                "Could not import pinecone python package. "
                "Please install it with `pip install pinecone-client`."
            )

        return cls(
            pinecone.Index(index_name), embedding.embed_query, text_key, namespace
        )