Error: Failed to find anything that looks like a service in module 'rrr'

i am completely new to nameko
when i run this below code i am getting a error -
Not Importing deprecated clients. Dependency Twisted is not Installed
Error: Failed to find anything that looks like a service in module ‘rrr’
how to solve this please kindly help me

from pymodbus.client.asynchronous.tcp import AsyncModbusTCPClient as ModbusClient
from pymodbus.client.asynchronous import schedulers
from nameko.rpc import rpc

UNIT = 0x1

class readregister:
    rr = "readregister"

async def start_async_test(client):

    rr = await client.read_coils(4146, 1, unit=255)
    print(rr)
    print(rr.function_code)


def run_with_no_loop():
    """
    ModbusClient Factory creates a loop.
    :return:
    """
    loop, client = ModbusClient(schedulers.ASYNC_IO,host='10.0.0.85', port=502)
    loop.run_until_complete(start_async_test(client.protocol))
    loop.close()

if __name__ == '__main__':
    run_with_no_loop()



@rpc
def run_sync_client():
    return start_async_test(client)