实现设备心跳检测（离线识别）

def solve():
    from pyodide.http import open_url
    from io import StringIO
    import pandas as pd
    devs_csv = open_url(____).read()
    logs_csv = open_url(____).read()
    devs = pd.read_csv(StringIO(____))
    logs = pd.read_csv(StringIO(____))
    HEARTBEAT_INTERVAL = ____
    MISS_THRESHOLD = ____
    OFFLINE_TIMEOUT = HEARTBEAT_INTERVAL * MISS_THRESHOLD
    now = logs['____'].max() + ____
    def check_heartbeat(____):
        dev_logs = logs[logs['____']==device_id]
        if dev_logs.empty: return '____', float(____)
        last_seen = dev_logs['____'].max()
        elapsed = now - last_seen
        if elapsed > OFFLINE_TIMEOUT: return '____', elapsed
        if elapsed > HEARTBEAT_INTERVAL: return '____', elapsed
        return '____', elapsed
    for _, dev in devs.iterrows():
        status, elapsed = check_heartbeat(____)
        print(dev['____'] + "____" + status + "____" + str(round(____)) + "____")