Need code for zombie arm animation

I am making a mod about custom zombies, and currently I am using Geckolib to help me animate the arm animation for idle, aggrovate and attack, but I wish there could be a way for me to have the arms move without Geckolib, and since I cant code, I need to copy the code from somewhere else. If you do have a code for such thing, please provide it to me, or at the least point me to where I can find such code.