Boolean tasks

I added ackerman.py and series.py.
>I was trying to say that
"if it doesn't have (m,r) ,return fibonacci(n),
if (m,r) = (2,1), which is sum_series(0) and sum_series(1) respectively,
return rucas(n),
else, return sum_series(n-2) + sum_series(n-1) with arbituary
sum_series(0)and sum_series(1).

To do this you would want to check the values bound to `m` and `r`. Something like:

    if m == 0 and r == 1:
        return fibonacci(n)

> I used my previous code and writed it like below.
Then the last test "assert sum_series(i, 2, 1) == lucas(i)" causes
AssertionError.

The `else` block in the version of `sum_series()` that you included in your comment is not quite correct. You need to pass the values of `m` and `r` to the recursive calls to `sum_series()` otherwise, those recursive calls will use the default values for `m` and `r`. Since the default values are the same as the first two numbers in the Fibonacci series it seems to work correctly when compared to `fibonacci()`, but fails when compared to `lucas()`.