human
Solve the following python programming problem given the following code:
def setup_platform(hass, config, add_devices_callback, discovery_info = None) : 
    'Setup the RFXtrx platform.' 
    from RFXtrx import SensorEvent 
    sensors = [] 
    for (packet_id, entity_info) in config ['devices'].items () : 
        event = rfxtrx.get_rfx_object (packet_id) 
        device_id = ('sensor_' + slugify (event.device.id_string.lower ())) 
        if (device_id in rfxtrx.RFX_DEVICES) : 
            continue 
_LOGGER.info ('Add %s rfxtrx.sensor', entity_info [ATTR_NAME]) 
        sub_sensors = { 
            
} 
        data_types = entity_info [ATTR_DATA_TYPE] 
        if (len (data_types) == 0) : 
            for data_type in DATA_TYPES : 
                if (data_type in event.values) : 
                    data_types = [data_type] 
                    break 
for _data_type in data_types : 
            new_sensor = RfxtrxSensor (event, entity_info [ATTR_NAME], _data_type) 
            sensors.append (new_sensor) 
            sub_sensors [_data_type] = new_sensor 
rfxtrx.RFX_DEVICES [sensor_update] = sub_sensors 
add_devices_callback (sensors) 
    def sensor_update(event) : 
        'Callback for sensor updates from the RFXtrx gateway.' 
        if (not isinstance (event, SensorEvent)) : 
            return 
device_id = ('sensor_' + slugify (event.device.id_string.lower ())) 
        if (device_id in rfxtrx.RFX_DEVICES) : 
            sensors = rfxtrx.RFX_DEVICES [device_id] 
            for key in sensors : 
                sensors [key].event = event 
return 
if (not config [ATTR_AUTOMATIC_ADD]) : 
            return 
pkt_id = ''.join (('{0:02x}'.format (x) for x in event.data)) 
        _LOGGER.info ('Automatic add rfxtrx.sensor: %s', device_id) 
        for data_type in DATA_TYPES : 
            if (data_type in event.values) : 
                new_sensor = RfxtrxSensor (event, pkt_id, data_type) 
                break 
sub_sensors = { 
            
} 
        sub_sensors [new_sensor.data_type] = new_sensor 
        rfxtrx.RFX_DEVICES [device_id] = sub_sensors 
       ...

    
    

    Fix the buggy line: rfxtrx.RFX_DEVICES [sensor_update] = sub_sensors
assistant
#Here is Python program to fix the buggy line: rfxtrx.

rfxtrx.RFX_DEVICES [device_id] = sub_sensors