requests ProxyError：重试与退避写法

import requests
from requests.adapters import HTTPAdapter
from urllib3.util import Retry

PROXY = "http://LOGIN:PASSWORD@HOST:2222"
PROXIES = {"http": PROXY, "https": PROXY}

retries = Retry(
    total=3,
    backoff_factor=1,
    status_forcelist=[429, 502, 503, 504],
    allowed_methods={"GET"},
)
session = requests.Session()
session.mount("https://", HTTPAdapter(max_retries=retries))
session.mount("http://", HTTPAdapter(max_retries=retries))

response = session.get("https://ipinfo.io/json", proxies=PROXIES, timeout=(3.05, 20))
print(response.status_code, response.text)

import random
import time

import requests

PROXY = "http://LOGIN:PASSWORD@HOST:2222"
PROXIES = {"http": PROXY, "https": PROXY}
RETRY_STATUS = {429, 502, 503, 504}
MAX_ATTEMPTS = 4


def fetch(url):
    last_error = None
    for attempt in range(1, MAX_ATTEMPTS + 1):
        delay = min(2 ** attempt, 30)  # 2, 4, 8, 16 seconds
        try:
            # a new Session opens a new connection, so a rotating line can give a new IP
            with requests.Session() as session:
                response = session.get(url, proxies=PROXIES, timeout=(3.05, 20))
            if response.status_code not in RETRY_STATUS:
                return response
            retry_after = response.headers.get("Retry-After", "")
            if retry_after.isdigit():
                delay = min(int(retry_after), 60)  # the server said how long to wait
            last_error = RuntimeError(f"HTTP {response.status_code}")
        except requests.exceptions.ProxyError as exc:
            if "407" in str(exc):
                raise  # wrong login: retrying will not help
            last_error = exc
        except (requests.exceptions.ConnectTimeout, requests.exceptions.ReadTimeout) as exc:
            last_error = exc
        if attempt < MAX_ATTEMPTS:
            time.sleep(delay + random.uniform(0, 1))
    raise RuntimeError(f"gave up after {MAX_ATTEMPTS} attempts: {last_error}")


if __name__ == "__main__":
    print(fetch("https://ipinfo.io/json").text)