Tkinter and Widget

[Golem]

Hi all !
I would like to know if there's a way to list all options that can be set
for a widget ?
In the Fredrik Lundh's Introduction To Tkinter, he says that we can use :
     keys() => list of all options available for this widget
I think that "keys" represent the widget (button, label)
So i try :

Mylist = Button()
for i in Mylist
      print i

But it doesn't work

How can we do that ?

Thkx

Golem