void add(Animatable animatable)

Adds the animatable to this juggler who will take care that it is animated.

When the animatable is finished it is automatically removed from this juggler. An animatable is finished as soon as it's advanceTime method returns false.

Source 

void add(Animatable animatable) {

  if (animatable is! Animatable) {
    throw new ArgumentError("The supplied animatable does not extend type Animatable.");
  }

  if (this.contains(animatable) == false) {
    var animatableLink = new _AnimatableLink();
    _lastAnimatableLink.animatable = animatable;
    _lastAnimatableLink.nextAnimatableLink = animatableLink;
    _lastAnimatableLink = animatableLink;
  }
}