repeateActionForever behind the scene

I would like to know how does the function "repeatActionForever" actually works behind the scene. I'm doing something similar that basically loops through different functions and perform them one by one, the only thing I can't figure out is how to make it an infinite loop so my code keeps repeating forever. Keep in mind that I don't want to use the actual "repeatActionForever" function, what I'm doing is mainly for me to learn the technique itself.


Any help would be much appreciated.