Override part of animation

:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By Pipe
:warning: Old Version Published before Godot 3 was released.

I have created 3 animations for a 2D character: idle, walk and sword attack, and structured them in a AnimationTreePlayer: enter image description here

Now I want to add a gun, for that i need to make one hand ignore the animations and rotate it as I wish to make it point through a script. How could I do that? I assume that if I tried to rotate it as it is now, the animation would also move the arm and freak out.