case 'For':
          return 'rgba(0,255,0,0.05)';
        case 'While':
          return 'rgba(0,0,255,0.05)';
        default:
          return 'rgba(0,0,0,0.05)';
      }
    }

    // define the Group template, required but unseen
    myDiagram.groupTemplate = new go.Group('Spot', {
      locationSpot: go.Spot.Center,
      layout: new ParallelLayout({ angle: 90, layerSpacing: 24, nodeSpacing: 30 }),
      mouseDragEnter: (e, group) => {
        var sh = group.findObject('SHAPE');
        if (sh) sh.str