'Turn on light child device.'

def _turn_on_light(self):

    set_req = self.gateway.const.SetReq
    if (self._state or (set_req.V_LIGHT not in self._values)):
        return
    self.gateway.set_child_value(self.node_id, self.child_id, set_req.V_LIGHT, 1)
    if self.gateway.optimistic:
        self._state = True
        self._values[set_req.V_LIGHT] = STATE_ON
        self.schedule_update_ha_state()
