anchor.diff:  
   const int Width= 1000;
   
  -CanvasRenderingContext2D context ;
  +
   
   
   @Component(
  
positive.code:     templateUrl: 'packages/mathlets/conditionalconvergence.html',
      cssUrl: 'packages/mathlets/conditionalconvergence.css',
      publishAs: 'cmp')
  class ConditionalConvergence{
    double accuExp = 0.0;
    
    var spacing = 5;
  
  
negative.code:   String targettxt;
  
    num target() => double.parse(targettxt);
  
    void onShadowRoot(ShadowRoot shadowRoot){
  //    accuExp = 2.0;
      CanvasRenderingContext2D context =
            (shadowRoot.querySelector("#canvas") as CanvasElement).context2D;
      drawLine(1,1, 20, 20, "red");
    }
    
    String result() =>
      "result" + printSeq(approxSeq(target(), example, pow(10.0, accuExp)));
  