Enjoyable and funny kata, congratulations for this one, it's nice finding out how it works.

You definetely can return a lambda function. Moreover, you can return lambda function from another lambda function.

can someone explain to me as to why you cant return a lambda function and give me some examples

Kata says function "takes a list of non-negative integers and strings"

approved.

python fork with new test framework

it should be non-negative...

Nice underestimated solution!

oh, thank you, i thought i need to split function calls and sub-function calls into a tuple. But they come together..

20 is the function return value: 8 + 12.

I read the description 3 times, but still can't understand a word...
Can someone explain why count_calls should return (0, 20) when there are 0 subfunction calls inside of the add function? (besides operator+, probably, but this is still far from 20)

def add(a, b):
return a + b

test.assert_equals(count_calls(add, 8, 12), (0, 20))

Very weird kata, but I had fun.