d a tree-parent reference to the base class name
        nodeDataArray.push({ key: k, parent: base.name });
      }
    }

    // Create the model for the hierarchy diagram
    diagram.model = new go.TreeModel(nodeDataArray);

    // Now collect all node data that are singletons
    var singlesArray = []; // for classes that don't inherit from another class
    diagram.nodes.each((node) => {
      if (node.linksConnected.count === 0) {
        singlesArray.push(node.data);
      }
    });

    // Remove the