Help in understanding some code!

[Wayne]

Hello,
I have  a Red Hat distro and I'm trying to emulate one of there
program's.
The program is netcfg.py The part that I'm trying to do is to allow the
user to click on a button, those that are at the top of the initial
window,
and get a form displayed.
The code that is at the end of this program reads as follows:

# magic to keep a root window from appearing
L = Label()
L.tk.call('wm','withdraw', '.')
del L

win = WindowFrame(Toplevel())
win.wait_window(win)

The whole program is over my head, but on my 5th reading I'm starting
to understand it I haven't figured out why they want to remove
the toplevel window and why do they have to create a labell to
do it. Also where will I find the syntax for the call statement.
I have a book title "Practical Programming in Tcl and Tk" by
Brent B Welch. I couldn find its use in the book.
TIA
Wayne