7. The method as in claim 1 wherein modifying at least some of the words in the first group of words includes: adjusting letters in words of the first group of words to form the second group of words.
7. The method as in claim 1 wherein modifying at least some of the words in the first group of words includes: adjusting letters in words of the first group of words to form the second group of words. 8. The method as in claim 7 wherein adjusting the letters in the words of the first group of words includes: for each word of the first group of words, making an adjustment to exactly one letter in that word to form a new word that is different from that word, the new word being included in the second group of words.