Hej all of you Anonimous Monks (couse I'm not sure if you are the same one posting all of the replies)
First of all, thank you for your time. I now understand use of return much better and will for sure benefit from that in the future. I see already where I need to modify my code. But I probably wouldn't get it if you didn't mention mathematical definition.
And as for reading, believe me I've read a (and still reading) Llama book, Camel book, CGI programming with perl, Intermediate Perl, Perl best practices, Perl cookbook. But when you're close to 50 it's not that easy to learn a new language (especially if it's not from your language group). That is as easy as learning Serbian if you are German or learning Swedish if you're Spanish, or learning Franch if you are Chinese. But I'm giving my best with "learning-by-doing" :-)