self.__docs_words = {}
self.__index = {}
# wewnatrz indeksu sa listy jak tutaj: self.__index['sell'] = [{'somedoc': 5, 'otherdoc': 13, ...}, 156]

# przed (wolne!):
for word in self.__docs_words[doc]:
    try:
        sum_of_mult_wages += (self.__index[word][0][doc]*self.__index[word][0][idoc])
    except KeyError:
        pass

# po (duuuuzo szybciej):
for word in self.__docs_words[doc]:
    sum_of_mult_wages += (self.__index[word][0][doc]*self.__index[word][0][idoc])