 and nodes
    myDiagram.findLayer('Tool').opacity = 0.5;

    // some common styles for most of the node templates
    function nodeStyle(obj={}) {
      return Object.assign({
        deletable: false,
        locationSpot: go.Spot.Center,
        mouseDragEnter: (e, node) => {
          var sh = node.findObject('SHAPE');
          if (sh) sh.fill = 'lime';
        },
        mouseDragLeave: (e, node) => {
          var sh = node.findObject('SHAPE');
          if (sh) sh.fill = 'white';
        },
       