anchor.diff:  }
   
   /// An oscillating curve that first grows and then shrink in magnitude.
  -class BounceInOutCurve implements Curve {
  +class BounceInOutCurve extends Curve {
     const BounceInOutCurve();
     double transform(double t) {
       if (t < 0.5)
  
positive.code: }
  
  /// An oscillating curve that grows and then shrinks in magnitude while overshooting its bounds.
  class ElasticInOutCurve implements Curve {
    const ElasticInOutCurve([this.period = 0.4]);
    final double period;
    double transform(double t) {
  
negative.code:   return 7.5625 * t * t + 0.984375;
  }
  
  /// A curve that is the reversed inversion of its given curve.
  class FlippedCurve extends Curve {
    FlippedCurve(this.curve);
    final Curve curve;
    double transform(double t) => 1.0 - curve.transform(1.0 - t);
  }
  
  /// An oscillating curve that grows in magnitude.
  class BounceInCurve extends Curve {
    const BounceInCurve();
    double transform(double t) {
      return 1.0 - _bounce(1.0 - t);
  