I can’t find what is wrong in my code. Yes, i have no background about programming.(sigh~)
Not much change required! 
Just define your variable lst1 so that the function knows that it’s a list that’s expected as input. That would be by typing a “:” followed by “var” as shown under.
For list of lists you can use “var…” (without the exclamation marks)
Oh, many Thanks, Jostein.