async def unsubscribe_callback(self, callback: Callback) -> bool:
    for (key, callbacks) in self._callbacks.items():
        if (callback in callbacks):
            callbacks.discard(callback)
            break
    else:
        return False
    if (not callbacks):
        (await self._master_api_client.unsusbcribe_param(key))
        self._cache.pop(key)
        self._callbacks.pop(key)
    return True
async def unsubscribe_callback(self, callback: Callback) -> bool:
    for (key, callbacks) in self._callbacks.items():
        if (callback in callbacks):
            callbacks.discard(callback)
            break
    else:
        return False
    if (not callbacks):
        (await self._master_api_client.unsusbcribe_param(key))
        self._cache.pop(key)
        self._callbacks.pop(key)
    return True