The following example will create a menu with the corresponding sub menu

 And here's the result   Remarks
 
 
  1. Handlers are to be individually created. Create a seperate file to hold them in your google apps script editor !
  2. Add createMenuItem to customise the sub menu
  3. Make sure to camel the naming. Use the ObjApp class +James Ferreirra created: ObjApp - class 
  4. Add menuItemSeparators make more distinction between menu items