|   | 1 |  initial version  | 
Hmmm . . . I couldn't figure it out either. The following does work:
s = 'fooooo'
t = 'baar'
print t + s[len(t):]
baaroo
Will that work in your situation?
 Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.
 
                
                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.