def is_similar(self, first, second):
    flag = False
    for ch in range(len(first)):
        if second[ch] != first[ch]:
            if flag is True:
                break
            flag = True
    else:
        return True
    return False

def test_get_same_words(self):
    first = 'кот'
    for word in test.get_similar(какие-то аргументы):
        self.assertTrue(self.is_similar(first, word))