calling upper() on a string, not working?

[John Salerno]

Bruno Desthuilliers wrote:

>> def encrypt_quote(original):
>       # Since it's here that we define that the new letters
>       # will be uppercase only, it's our responsability
>       # to handle any related conditions and problems
>       # The other functions shouldn't have to even know this.
>       original = original.upper()

>> def filter_letters(original):
>       # here, we *dont* have to do anything else than filtering
>       # upper/lower case is *not* our problem.
>>     return ''.join(set(original) - PUNCT_SPACE_SET)

Thanks, I was wondering if it only needed to be done in a single place 
like that.