'Turn on a led.'

def turn_on(self, **kwargs):

    if (ATTR_BRIGHTNESS in kwargs):
        self._brightness = kwargs[ATTR_BRIGHTNESS]
    if (ATTR_TRANSITION in kwargs):
        transition_time = kwargs[ATTR_TRANSITION]
        self._led.transition(transition_time, is_on=True, brightness=_from_hass_brightness(self._brightness))
    else:
        self._led.set(is_on=True, brightness=_from_hass_brightness(self._brightness))
    self._is_on = True
    self.schedule_update_ha_state()
