human
Solve the following python programming problem given the following code:
def Transform(self, client, device, callback) : 
    from tornado.web import stack_context 
    from viewfinder.backend.db.device import Device 
    def _DoUpdate() : 
        self._LogUpdate (device) 
        if Version._mutate_items : 
            device.Update (client, partial (callback, device)) 
else : 
            callback (device) 
def _OnQueryByPushToken(other_devices) : 
        for other in other_devices : 
            if ((other.push_token == device.push_token) and (other.device_id > device.device_id)) : 
                device.alert_user_id = None 
                device.push_token = None 
                break 
_DoUpdate () 
if (InTransformContext.current () is None) : 
        with stack_context.StackContext (InTransformContext ()) : 
            device.timestamp = (device.last_access or time.time ()) 
            if (_OnQueryByPushToken.push_token is not None) : 
                if (time.time () < (device.last_access + Device._PUSH_EXPIRATION)) : 
                    device.alert_user_id = device.user_id 
query_expr = ('device.push_token={t}', { 
                    't' : device.push_token, 
}) 
                Device.IndexQuery (client, query_expr, None, _OnQueryByPushToken) 
else : 
                _DoUpdate () 
else : 
        callback (device) 

    
    

    Fix the buggy line: if (_OnQueryByPushToken.push_token is not None) :
assistant
#Here is Python program to fix the buggy line: if (_OnQueryByPushToken.

if (device.push_token is not None) :