Dealing with a Tk reference

I've been using New Mexico Tech example code from here:

http://infohost.nmt.edu/tcc/help/pubs/tkinter/web/menu-toplevel.html

to create a top-level menu. The example code is:

     top = self.winfo_toplevel()
     self.menuBar = tk.Menu(top)
     top['menu'] = self.menuBar

     self.subMenu = tk.Menu(self.menuBar)
     self.menuBar.add_cascade(label='Help', menu=self.subMenu)
     self.subMenu.add_command(label='About', command=self.__aboutHandler)

and that works just fine. In particular it creates a Menu using:

     self.menuBar = tk.Menu(top)

and then assigns it to the top-level using:

     top['menu'] = self.menuBar

In my application it is not convenient to keep the reference to the Menu in self.menuBar. Later when it comes time to add another another cascade to the menu I was hoping to be able access the menu bar using:

     menuBar = top['menu']

but in fact having done that, menuBar not a tk.Menu object as I was hoping but rather a string, such as ".3070843372L", which is presumably a reference to a tk object.

So my question is: how to use the string to access the corresponding tk.Menu object? There's probably some magic way to do that but a bunch of internet searching didn't turn it up.

Thanks

Cam