return self.cache[self.cache_index - 1]

 def build_match_and_apply_functions(pattern, search, replace):
     def matches_rule(word):
        return re.search(pattern, word)
     def apply_rule(word):
        return re.sub(search, replace, word)
     return (matches_rule, apply_rule)
def plural(noun):
      for matches_rule, apply_rule in rules:
         if matches_rule(noun):
            return apply_rule(noun)
      raise ValueError('no matching rule for {0}'.format(noun))

  
def matches_rule(word):

  
if matches_rule(noun):

  
if matches_rule('abc'):

  
>>> def f(n):
...   return n * n
... 
>>> f(3)
9
>>> f(5)
25
>>> x = 4
>>> f(x)
16
>>>

 import re
import itertools
def solve(puzzle):
    words = re.findall('[A-Z]+', puzzle.upper())
    unique_characters = set(''.join(words))
    assert len(unique_characters) <= 10, 'Too many letters'
    first_letters = {word[0] for word in words}
    n = len(first_letters)
    sorted_characters = ''.join(first_letters) + \
        ''.join(unique_characters - first_letters)
    characters = tuple(ord(c) for c in sorted_characters)
    digits = tuple(ord(c) for c in '0123456789')
    zero = digits[0]
    for guess in itertools.permutations(digits, len(characters)):
        if zero not in guess[:n]:
            equation = puzzle.translate(dict(zip(characters, guess)))
            if eval(equation):
                return equation
if __name__ == '__main__':
    import sys
    for puzzle in sys.argv[1:]:
        print(puzzle)
        solution = solve(puzzle)
        if solution:
            print(solution)

 first_letters = {word[0] for word in words}
n = len(first_letters)
sorted_characters = ''.join(first_letters) + \
    ''.join(unique_characters - first_letters)

 characters = tuple(ord(c) for c in sorted_characters)
digits = tuple(ord(c) for c in '0123456789')

 equation = puzzle.translate(dict(zip(characters, guess)))

 roman_numeral_map = (('M',  1000),
                     ('CM', 900),
                     ('D',  500),
                     ('CD', 400),
                     ('C',  100),
                     ('XC', 90),
                     ('L', 50),
                     ('XL', 40),
                     ('X', 10),
                     ('IX', 9),
                     ('V', 5),
                     ('IV', 4),
                     ('I', 1))
def to_roman(n):
    '''converts integers to Roman numerals'''
    if not (0 < n < 4000):
        raise OutOfRangeError('Number out of range (must be 1...3999)')
    if not isinstance(n, int):
        raise NotIntegerError('non-integers cannot be converted')
    result = ''
    for numeral, integer in roman_numeral_map:
        while n >= integer:
            result += numeral
            n -=integer
    return result

 def from_roman(s):
    '''converts Roman numerals to integers'''
    result = 0
    index = 0
    for numeral, integer in roman_numeral_map:
        while s[index:index+len(numeral)] == numeral:
            result += integer
            index += len(numeral)
    return result

 index:index+len(numeral)