utoScale.Uniform,
      maxSelectionCount: 1, // users can select only one part at a time
      validCycle: go.CycleMode.DestinationTree, // make sure users can only create trees
      layout: new SideTreeLayout({
        treeStyle: go.TreeStyle.LastParents,
        arrangement: go.TreeArrangement.Horizontal,
        // properties for most of the tree:
        angle: 90,
        layerSpacing: 35,
        // properties for the "last parents":
        alternateAngle: 90,
        alternateLayerSpacing: 35,
   