langchain/requests.py/Requests/_arequest
class Requests:    async def _arequest(
        self, method: str, url: str, **kwargs: Any
    ) -> AsyncGenerator[aiohttp.ClientResponse, None]:
        """Make an async request."""
        if not self.aiosession:
            async with aiohttp.ClientSession() as session:
                async with session.request(
                    method, url, headers=self.headers, **kwargs
                ) as response:
                    yield response
        else:
            async with self.aiosession.request(
                method, url, headers=self.headers, **kwargs
            ) as response:
                yield response