How to make a lightning flash (extending tutorial...)

I have followed the tutorial: Unity Quick Script - Flickering Light - YouTube

I have copied out the code at 1m 20s and it makes the light flash on and off (in my case a direction light which is very bright).

How do i change the script to make it so when the light is on, it stays on ONLY for 2 frames of rendered animation, and then turns off… THEN follows the randomized delay?

(I am on unity 2019.2.0f1 - the topic tags appear to be like unity4/5 so i dunno what to tag this with).

I should probably clarify “2 frames of rendered animation” means 2 frames/fps of gameplay, not any kind of animation, i.e. 1 30th of a second if game is running at 60fps.