Turns off the light by gradually fading it out.
        The optional `duration` parameter allows for control
        of the fade out duration (in seconds)

def fade_out(self, duration=3, group=0):
        """Turns off the light by gradually fading it out.
        The optional `duration` parameter allows for control
        of the fade out duration (in seconds)"""
        self.on(group)
        super(WhiteLight, self).fade_out(duration, group=group)
        self.off(group)