anchor.diff:  
   typedef double Easing(double t);
   
  -
   final Map<String, Easing> MapStringToEasing = {
     "Cosine": EasingCosine,
     "Sine": EasingSine,
  
positive.code:   return out;
  }
  
  List<List<VM.Vector3>> BevelStrips(List<VM.Vector2> contour,
      List<VM.Vector2> gradient, List<VM.Vector2> supports, VM.Matrix3 m) {
    assert(contour.length == gradient.length);
  
negative.code:                        x
  
   */
  // Easing functions (aka inbetweening or tweening) map
  // [0, 1] => [0, 1]
  // You can visualize each function by googling the expression
  // which will bring up google's graphing calculator, e.g.:
  // 1 - cos(x * pi / 2)
  // sin(x * pi / 2)
  //
  // References:
  // http://gizma.com/easing/
  
  double EasingCosine(double t) => 1.0 - Math.cos(t * Math.PI / 2);
  
  