def make_product(*values):
    def fold((n, l), v):
        (n, m) = divmod(n, len(v))
        return (n, l + [v[m]])
    def product(n):
        (n, l) = reduce(fold, values, (n, []))
        if n > 0: raise StopIteration
        print ''.join(map(str, l))
        return ''.join(map(str, l))
    return product

def product_from(n, *values):
    return imap(make_product(*values), count(n))

myString = list(product_from(0, ['a','b','c'], ['a','b','c']))