langchain/retrievers/remote_retriever.py/RemoteLangChainRetriever/aget_relevant_documents
class RemoteLangChainRetriever:    async def aget_relevant_documents(self, query: str) -> List[Document]:
        async with aiohttp.ClientSession() as session:
            async with session.request(
                "POST", self.url, headers=self.headers, json={self.input_key: query}
            ) as response:
                result = await response.json()
        return [
            Document(
                page_content=r[self.page_content_key], metadata=r[self.metadata_key]
            )
            for r in result[self.response_key]
        ]