human
Here's a good function header given the following:
I wrote the below code

    import velbus
    port = config[DOMAIN].get(CONF_PORT)
    connection = velbus.VelbusUSBConnection(port)
    controller = velbus.Controller(connection)
    hass.data[DOMAIN] = controller
    def stop_velbus(event):
        'Disconnect    from    serial    port.'
        _LOGGER.debug('Shutting    down    ')
        connection.stop()
    hass.bus.listen_once(EVENT_HOMEASSISTANT_STOP, stop_velbus)
    return True

What's a good function header?
assistant
#Here's a good function header.

def setup(hass, config):