Builder function used by widgets to update your scene when animating.
It has the pattern context, child and value.
context is your Flutter BuildContext.
child is any widget that is not effected by the
animation. Flutter doesn't need to rebuild that
widget when the animation updates. This way you can
improve the performance of your animation.
value is current value of your animated property.
typedef AnimatedWidgetBuilder<T> = Widget Function( BuildContext context, Widget? child, T value);