Why not compare the first character of the input to y or n (forced lower), or only allow one character of input like the instructions show.

Updated it to your suggestion.

One more suggestion, make sure to test against lower case:

   reply = str(raw_input(question+' (y/n): ')).lower()

You could even add .strip() on there if you want to make sure it doesn't have leading spaces.

Another good one, thanks.

Wouldn't everybody save much more time just using Common Lisp, and its already existing (y-or-n-p) function?