langchain/chains/router/embedding_router.py/EmbeddingRouterChain/from_names_and_descriptions
class EmbeddingRouterChain:    def from_names_and_descriptions(
        cls,
        names_and_descriptions: Sequence[Tuple[str, Sequence[str]]],
        vectorstore_cls: Type[VectorStore],
        embeddings: Embeddings,
        **kwargs: Any,
    ) -> EmbeddingRouterChain:
        """Convenience constructor."""
        documents = []
        for name, descriptions in names_and_descriptions:
            for description in descriptions:
                documents.append(
                    Document(page_content=description, metadata={"name": name})
                )
        vectorstore = vectorstore_cls.from_documents(documents, embeddings)
        return cls(vectorstore=vectorstore, **kwargs)