Python3 Websocket回调无法分配类成员函数

import websockets

class WebSocketServer:
    def __init__(self):
        self.websocket = None

    async def handle_message(self, message):
        # 处理接收到的消息
        pass

    def websocket_handler(self, websocket):
        self.websocket = websocket
        while True:
            message = await websocket.recv()
            await self.handle_message(message)

    def start_server(self):
        start_server = websockets.serve(self.websocket_handler, 'localhost', 8765)
        asyncio.get_event_loop().run_until_complete(start_server)
        asyncio.get_event_loop().run_forever()

# 使用装饰器将类的成员函数转换为普通函数
def websocket_handler_wrapper(server):
    async def wrapper(websocket):
        await server.websocket_handler(websocket)
    return wrapper

if __name__ == '__main__':
    server = WebSocketServer()
    start_server = websockets.serve(websocket_handler_wrapper(server), 'localhost', 8765)
    asyncio.get_event_loop().run_until_complete(start_server)
    asyncio.get_event_loop().run_forever()