anchor.diff:  /// animation's duration. Each tween defines the animation's value during the
   /// interval indicated by its weight.
   ///
  -/// For example, to define an animation that uses an easing curve to interpolate
  -/// between 5.0 and 10.0 during the first 40% of the animation, remain at 10.0
  -/// for the next 20%, and then return to 10.0 for the final 40%:
  +/// {@tool sample}
  +/// This example defines an animation that uses an easing curve to interpolate
  +/// between 5.0 and 10.0 during the first 40% of the animation, remains at 10.0
  +/// for the next 20%, and then returns to 5.0 for the final 40%.
   ///
   /// ```dart
   /// final Animation<double> animation = TweenSequence(
  
positive.code: ///   ],
  /// ).animate(myAnimationController);
  /// ```
  class TweenSequence<T> extends Animatable<T> {
    /// Construct a TweenSequence.
    ///
  
negative.code: import 'animation.dart';
  import 'tween.dart';
  
  // Examples can assume:
  // AnimationController myAnimationController;
  
  /// Enables creating an [Animation] whose value is defined by a sequence of
  /// [Tween]s.
  ///
  