Polyline animation

Hello! I very new in Cesium and I have problems with animation of my arrow entity. So I have arrow entity:

var arrow = viewer.entities.add({
    name : 'Purple straight arrow at height',
    polyline : {
        positions : Cesium.Cartesian3.fromDegreesArrayHeights([100, 100, 0, 150, 150, 0]),
        width : 10,
        followSurface : true,
        material : new Cesium.PolylineArrowMaterialProperty(Cesium.Color.BLUE),
    show: false

Tell me please, how can I move this arrow to abother coordinates, with animation of movement?Please give me whole code to do this!
(I alredy tryed to move arrow by updating it's posistion in while loop, but there is no animation, only end position was show. )


Please see my answer in this post: https://groups.google.com/d/msg/cesium-dev/3zHCkexUFc4/ysIceMHUBQAJ

There is a code example there to show you how to animate a polyline using a CallbackProperty for the positions.



Thanks a lot!