Thank you so much.

can you give me a hint how your code works? I tried to find out by myself and I understand that your code is related to recursion in python and not only, yet I still can't understand why after returning your forth line your code still works. Thank you in advance

I can't understand why I fail this kind of tests:
It should work for random inputs too: 'kgiujjkfvgtjiloozzxvnfrydgdowmnshvene' should equal 'kgi u jjkfv gtjiloozzxvnfrydgdowmnsh vene'
My question is: in the output we must keep space or not? I'm asking because the main test looks like this : (de_nico("crazy","cseerntiofarmit on "),"secretinformation") and I can pass all main tests...