More realistic lru_cache example (gh-144517)

Author: rhettinger

Doc/library/functools.rst

@@ -180,8 +180,8 @@ The :mod:`functools` module defines the following functions:
    the *maxsize* at its default value of 128::
 
        @lru_cache
-       def count_vowels(sentence):
-           return sum(sentence.count(vowel) for vowel in 'AEIOUaeiou')
+       def count_vowels(word):
+           return sum(word.count(vowel) for vowel in 'AEIOUaeiou')
 
    If *maxsize* is set to ``None``, the LRU feature is disabled and the cache can
    grow without bound.