How to speed up Pixi.spine.Spine instance?

Hi guys, i'm using pixi.js (ver 3.0.7) with plugin pixi-spine.js (version 2.1), everything works fine but when I tried this:

var test = new PIXI.spine.Spine(res.spine.spineData);

test.animationSpeed = 2;

it doen't work.

I was wondering if the API has been changed....hmm,anyone knows how to speed up/down the animation speed (or maybe frame rate) of an instance of the PIXI.spine.Spine?

Hope you guys can give me a hand,it would be great help