TweenSequence.dart

final offsetAnimation = TweenSequence([
              TweenSequenceItem(
                  tween: Tween<Offset>(
                      begin: Offset(0.0, 1.0), end: Offset(0.0, 0.0)),
                  weight: 1),
              TweenSequenceItem(
                  tween: ConstantTween(Offset(0.0, 0.0)), weight: 3),
              TweenSequenceItem(
                  tween: Tween<Offset>(
                      begin: Offset(0.0, 0.0), end: Offset(0.0, -1.0)),
                  weight: 1)
            ]).animate(animation);