for i in range(retries):
                try:
                    async with session.get(
                        url, headers=self.session.headers
                    ) as response:
                        return await response.text()
                except aiohttp.ClientConnectionError as e:
                    if i == retries - 1:
                        raise
                    else:
                        logger.warning(
                            f"Error fetching {url} with attempt "
                            f"{i + 1}/{retries}: {e}. Retrying..."
                        )
                        await asyncio.sleep(cooldown * backoff**i)
        raise ValueError("retry count exceeded")
    async def _fetch_with_rate_limit(
        self, url: str, semaphore: asyncio.Semaphore
    ) -> str:
        async with semaphore:
            return await self._fetch(url)
[docs]    async def fetch_all(self, urls: List[str]) -> Any:
        """Fetch all urls concurrently with rate limiting."""
        semaphore = asyncio.Semaphore(self.requests_per_second)
        tasks = []
        for url in urls:
            task = asyncio.ensure_future(self._fetch_with_rate_limit(url, semaphore))
            tasks.append(task)
        try:
            from tqdm.asyncio import tqdm_asyncio
            return await tqdm_asyncio.gather(
                *tasks, desc="Fetching pages", ascii=True, mininterval=1
            )
        except ImportError:
            warnings.warn("For better logging of progress, `pip install tqdm`")
            return await asyncio.gather(*tasks)
    @staticmethod
    def _check_parser(parser: str) -> None:
        """Check that parser is valid for bs4."""
        valid_parsers = ["html.parser", "lxml", "xml", "lxml-xml", "html5lib"]
        if parser not in valid_parsers:
            raise ValueError(
rtdocs_stable/api.python.langchain.com/en/stable/_modules/langchain/document_loaders/web_base.html