 the properties of the selected person in HTML
    myInspector = new Inspector('myInspector', myDiagram, {
      properties: {
        key: { readOnly: true },
        comments: {},
        isAssistant: { type: 'boolean', defaultValue: false }
      },
      propertyModified: (name, val) => {
        if (name === 'isAssistant') myDiagram.layout.invalidateLayout();
      }
    });
  } // end init

  // Assume that the SideTreeLayout determines whether a node is an "assistant" if a particular data property is