hi can someone help please key bind

Sat Oct 15 13:30:59 EDT 2011

Hi im trying to use key bind on Tkinter to call this function
def Start():
 for i in range(60,-1,-1):
 ent['text'] = i
 time.sleep(1)
 root.update()
 ent['text'] = 'Time Out!'
 root.update()
i know the function is ok as i have assigned a button and i calls the 
function as i expect
but
root.bind('<a>',Start)
gives the following error
Exception in Tkinter callback
Traceback (most recent call last):
 File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1413, in __call__
 return self.func(*args)
TypeError: Start() takes no arguments (1 given)
Thanks