Future<Null> forward({double from })

Starts running this animation forwards (towards the end).

Returns a Future that completes when the animation is complete.

Source 

Future<Null> forward({ double from }) {
  assert(() {
    if (duration == null) {
      throw new FlutterError(
        'AnimationController.forward() called with no default Duration.\n'
        'The "duration" property should be set, either in the constructor or later, before '
        'calling the forward() function.'
      );
    }
    return true;
  });
  _direction = _AnimationDirection.forward;
  if (from != null)
    value = from;
  return animateTo(upperBound);
}