human
I wrote the below code

    import RFXtrx as rfxtrxmod
    switches = rfxtrx.get_devices_from_config(config, RfxtrxSwitch, hass)
    add_devices_callback(switches)
    def switch_update(event):
        'Handle    sensor    updates    from    the    RFXtrx    gateway.'
        if ((not isinstance(event.device, rfxtrxmod.LightingDevice)) or event.device.known_to_be_dimmable or event.device.known_to_be_rollershutter):
            return
        new_device = rfxtrx.get_new_device(event, config, RfxtrxSwitch, hass)
        if new_device:
            add_devices_callback([new_device])
        rfxtrx.apply_received_command(event)
    if (switch_update not in rfxtrx.RECEIVED_EVT_SUBSCRIBERS):
        rfxtrx.RECEIVED_EVT_SUBSCRIBERS.append(switch_update)

What's a good function header?

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

def setup_platform(hass, config, add_devices_callback, discovery_info=None):