public static Tween cycle(Tween delegate) {
        return sequence(delegate, invert(delegate));
    }
Creates a tween that will cycle back and forth the specified delegate tween.
When reaching the end, the tween will play backwards from the end until it
reaches the start.

@param delegate the desired tween
@return a new instance
jme3-core/src/main/java/com/jme3/anim/tween/Tweens.java