Python • Re: MQTT JSON use data outside function

Code:

import asyncioimport randomimport jsonfrom dataclasses import dataclass, asdictfrom aiomqtt import Client@dataclassclass SensorData:    """    Structure of SensorData    """    value: float    unit: str    name: str    @property    def json(self):        return json.dumps(asdict(self))def read_sensor_1() -> SensorData:    # this could be your sensor data    value = random.uniform(0,10)        return SensorData(value=value, unit="m/s", name="Sensor 1")async def reader(client: Client):    async for msg in client.messages:        print(msg.payload)async def writer(client: Client):    while True:        await asyncio.sleep(5)        # sending sensor data as str (json)        # read_sensor_1() returns SensorData        # and SensorData has one property called json        # which does the conversion from        # dataclass > dict > json-str        await client.publish("/sensor1", read_sensor_1().json)async def MQTT():    """    Opens a connection to MQTT-Broker @localhost    Subscribes /receive    Starts two tasks in a TaskGroup    one reader, one writer    If one of the tasks throws an Exception    it bubbles up to the caller    """    async with Client("localhost") as client:        print("Connected")        await client.subscribe("/receive")        print("/receive subscribed")        async with asyncio.TaskGroup() as tg:            tg.create_task(reader(client))            tg.create_task(writer(client))async def main():    while True:        try:            print("Connecting")            await MQTT() # <- this coroutine could throw an exception        except *Exception as e:            # TaskGroups do have more than one exception            for exc in e.exceptions:                print(f"Exception: {exc}")        finally:            await asyncio.sleep(10)               print("Trying to reconnect")if __name__ == "__main__":    # for windows    asyncio.run(main(), loop_factory=asyncio.SelectorEventLoop)    # for linux    # asyncio.run(main())