I want to flash the traffic light in the gazebo, but I don't know how. I found a Flashlight Plugin but I don't know how to do it I want to flash the traffic light in the gazebo, but I don't know how. I found a Flashlight Plugin but I don't know how to do it I would be glad if you help me very important

http://gazebosim.org/tutorials?tut=flashlight_plugin&cat=plugins