Websocket nested on_message function returning none / correct value

I'm trying to create nested functions in my WebSocket so I can send multiple different messages in the TCP conn. In addition, I'm trying to figure out how to alter the response so that it won't return a value if the response is not none.

import websocket
class Opcode:
    CONNECTED       = '40{"sid"'
class Server:
    '''
    This class is our middleman between us and atshop,
    and it handles everything related to websockets.
    '''

    def __init__(self):
        self._connected = False
        self._websocket = self.create_websocket()

        self.run()

    def create_websocket(self):
        return websocket.WebSocketApp(
            url='wss://websocket.net',
            header={
                'Accept-Encoding': 'gzip, deflate, br',
                'Accept-Language': 'en-US,en;q=0.7',
                'Cookie': '', #some auth cookie
                'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.5112.102 Safari/537.36'
            },
            on_open=lambda ws: self.on_open(ws),
            on_message=lambda ws, msg: self.on_message(ws, msg),
            on_error=lambda ws, msg: self.on_error(ws, msg),
            on_close=lambda ws, close_code, close_msg: self.on_close(ws, close_code, close_msg)
        )

    def on_open(self, ws):
        self._websocket.send('40') #inn con

    def on_close(self, ws, close_code, close_msg): #conn close
        print('Connection is closing.')

    def on_error(self, ws, error):
        raise Exception(error)

    def on_message(self, ws, message):
        def send_message(sentMessage, response):
            if Opcode.CONNECTED in message: 
                self._websocket.send(sentMessage)
            if response in message:
                return(message)
        print(send_message())
    def run(self):
        self._websocket.run_forever(
            ping_interval=30,
            ping_timeout=10
        )  

if __name__ == '__main__':
    Server = Server()

My problem is that this will send a 2 - 5 responses of None then return the "response" value then countinously return a None value.

What I tried to do:

    def on_message(self, ws, message):
        def send_message(sentMessage, response):
            while True:
                if Opcode.CONNECTED in message:
                    self._websocket.send(sentMessage)
                if response in message:
                    return(message)
        print(send_message())
``` <- this code does not work.