Okay, so we wish to return
mississippi. The word
unique is ambiguous in this context since only the
m is unique, the rest are similar, but make up the other three distinct letters.
As for the
letters string, that’s as much as saying,
letter.isalpha() to prevent non-alpha characters from being included in the count. Not sure, but I think the only other place we see
isalpha() is in the Pyg Latin exercise.