Python sleep doesn't work right in a loop?

[ritterhaus at yahoo.com]

Just a simple bit of code to toggle between two state at intervals...

import time
for i in range(4):
    print 'On'
    time.sleep(1)
    print 'Off'
    time.sleep(1)

... SHOULD toggle On and Off four times with one-second pauses. When I
run this, the loop pauses the full eight seconds then prints the Ons
and Offs all at once. What's up with that?