Python: Числовые ребусы

Программка для разгадывания числовых ребусов. Методом грубой силы (т.е. простым перебором).

#!/usr/bin/env python
# -*- coding: UTF-8 -*-

import sys

#equation = u'удар+удар==драка'
#equation = u'кошка+кошка+кошка==собака'
#equation = u'кто+умён+тот==силён'
#equation = u'где*где-всюду==везде'
equation = u'масло+ноль==омлет'

def replace_all(text, srch, repl):
    for i in range(0, len(srch)):
        text = text.replace(srch[i], repl[i])
    return text

letters = []

for l in equation:
    if l not in ('+', '=', '-', '*'):
        if l not in letters:
            letters.append(l)

tops, counters = [], []
for i in range(0, len(letters)):
    tops.append(10 - i)
    counters.append(0)

canExit = False
while(not(canExit)):

    numbers = ['0','1','2','3','4','5','6','7','8','9']
    substs = []
    for i in range(0, len(tops)):
        substs.append(numbers[counters[i]])
        del numbers[counters[i]]

    text = replace_all(equation, letters, substs)
    try:
        if eval( text ):
            print text
    except:
        None

    N = 0
    inc = 1
    while (N < len(counters) and inc > 0):
        counters[N] += inc
        inc = 0
        if (counters[N] == tops[N]):
            counters[N] = 0
            inc = 1
            N += 1

    canExit = True
    for i in range(0, len(tops)):
        canExit &= (counters[i] == tops[i]-1)