Ravn from Python, with requests

import os
import time
import requests

API = "https://api.askravn.com/v1/tools/"
SESSION = requests.Session()
SESSION.headers["Authorization"] = "Bearer " + os.environ["RAVN_API_KEY"]


class RavnError(Exception):
    def __init__(self, http, code, message):
        super().__init__(f"{http} {code}: {message}")
        self.http, self.code = http, code


def call(tool, payload, max_wait=300, tries=4):
    """Returns results dict/list, or None on a free not_found miss."""
    for attempt in range(tries):
        r = SESSION.post(API + tool, json=payload, timeout=60)
        if r.status_code == 429:
            wait = int(r.headers.get("Retry-After", "30"))
            if wait > max_wait:  # 5-hour window is full: don't sleep for hours
                raise RavnError(429, r.json()["error"]["code"], f"retry in {wait}s")
            time.sleep(wait)
            continue
        if r.status_code == 503 and attempt < tries - 1:
            time.sleep(2 ** attempt)
            continue
        body = r.json()
        if r.status_code != 200:
            err = body["error"]
            raise RavnError(r.status_code, err["code"], err["message"])
        return body["results"] if body["status"] == "ok" else None
    raise RavnError(r.status_code, "gave_up", "retries exhausted")


if __name__ == "__main__":
    v = call("validate_email", {"email": "jane@acme.com"})
    if v is None:
        print("no verdict")
    elif v["status"] == "valid" and v["risk_score"] in ("A", "B"):
        print("send")
    elif v["status"] == "risky":
        print("review:", v["reason"])  # e.g. catch_all_domain
    else:
        print("drop:", v["reason"])

    for v in call("validate_emails", {"emails": ["a@acme.com", "b@acme.com"]}) or []:
        print(v["email"], v["status"], v["risk_score"])