That's the reason of my answer but I am doing my best. Anyway I asked this 4 months ago and now I understand it and noticed is pretty obvious. Thanks for the answer.

There is some recursion there. Please deep your knowledge about it!

nice smart love it!

Oh, I see. Thanks so much!

It's just recursion, first return calls the same function while changing the argument, but in this case it looks redundant, you can achieve same results with simple loop. Second return just returns value when you reached your condition and don't need to make more calls.

Can anyone tell me the reason of two returns? Newbie dumb here in Python. Thanks.

just hope years doesn't get over 1000 lol

good use of recursion

Cool recursive solution ... however, for people who might actually think this is best practice:
For a problem like this you should only do recursion in a language thats supports tail call optimization.
Python does not (at least out of the box at this time as I understand)
There really should be a clear reason for recursion, usually clarity. In this case I don't see it - but meh - that's subjective.

that's the juice of genius

Clever recursion, good show!

It will work but I believe looping would be more efficient.

Agree, I don't think this solution the best practice.

recursion is inefficient compared to loop

it's when fucntion calls itself