s(coll, false);
      myDiagram.commitTransaction('detach');
    }

    // no visual representation of any link data
    myDiagram.linkTemplate = new go.Link({ visible: false });

    // support optional links from comment nodes to pipe nodes
    myDiagram.linkTemplateMap.add(
      'Comment',
      new go.Link({ curve: go.Curve.Bezier })
        .add(
          new go.Shape({ stroke: 'brown', strokeWidth: 2 }),
          new go.Shape({ toArrow: 'OpenTriangle', stroke: 'brown' })
        )
    );

    // th