Maintain a live price book

import json, os
from websockets.sync.client import connect

KEY = os.environ["MAGICMARKETS_API_KEY"]
book = {}
events = {}

def key(p):
    return (p["sport"], p["event_id"], p["bet_type"])

def best(price_list):
    return price_list[0]["effective"]["price"] if price_list else None

with connect(f"wss://magicmarkets.com/v2/stream?api_key={KEY}") as ws:
    synced = False
    while not synced:
        for entry in json.loads(ws.recv())["data"]:
            if entry[0] == "event":
                events[entry[1]["event_id"]] = entry[1]
            elif entry[0] == "sync":
                synced = True

    for ev in list(events.values())[:10]:
        ws.send(json.dumps(["register_event", ev["sport"], ev["event_id"]]))

    while True:
        for entry in json.loads(ws.recv())["data"]:
            tag = entry[0]
            p = entry[1] if len(entry) > 1 else None
            if tag == "offer":
                book[key(p)] = p["price_list"]
            elif tag == "remove_offer":
                book.pop(key(p), None)
            elif tag == "event":
                events[p["event_id"]] = p
            elif tag == "remove_event":
                events.pop(p["event_id"], None)
                for k in [k for k in book if k[1] == p["event_id"]]:
                    del book[k]
            elif tag == "clear_events":
                book.clear()
                events.clear()

for (sport, event_id, bet_type), pl in book.items():
    if bet_type.startswith("for,") and pl:
        print(events[event_id]["event_name"], bet_type, best(pl), pl[0]["effective"]["max"])