Yes it needs refinement, but it was created to only be used as an example of how you could achieve knocking back, the only real part of the example is the one line of code where it knocks the player backwards. Everything else is just in there should I ever want to continue on with it, but I won't because as Vrav said, it doesn't work very well and the maths are pretty far off. Plus, I also encountered a weird bug where the player sprite did not register collisions anymore and instead I had to create an awkward collision mask for it. This is very buggy and the only part of it I suggest you look at is the knockback event.