Retry on 429 with backoff

# curl's built-in retry honors Retry-After on 429/503:
curl --retry 5 --retry-delay 1 --retry-max-time 60 \
  --retry-all-errors https://api.example.com/data

async function withRetry(url, opts = {}, max = 5) {
  for (let i = 0; i < max; i++) {
    const res = await fetch(url, opts);
    if (res.status !== 429) return res;
    const ra = res.headers.get('Retry-After');
    const waitMs = ra ? Number(ra) * 1000
                      : Math.min(2 ** i * 1000, 30000);
    const jitter = Math.random() * 250;
    await new Promise(r => setTimeout(r, waitMs + jitter));
  }
  throw new Error('rate limited: retries exhausted');
}

import time, random, requests

def get_with_retry(url, tries=5):
    for i in range(tries):
        r = requests.get(url)
        if r.status_code != 429:
            return r
        ra = r.headers.get('Retry-After')
        wait = float(ra) if ra else min(2 ** i, 30)
        time.sleep(wait + random.uniform(0, 0.25))  # jitter
    raise RuntimeError('rate limited')