RM Example: How to set a random delay between X and Y minutes


For some of my pistons I like to have a random delay between X and Y minutes. This way when we are away, the lights do not always turn off at the same time at night and hopefully give the impression that someone is home.
I did a work around using 2 pistons before @bravenel pointed me in the right direction to do this in one rule. I just thought I would share this in case anyone else was wondering how to do this.
For this example rule I want a random delay between 20 and 60 minutes before turning off the lights.