its less readable to me . isnt good python code meant to be easy to read

Thank you.
Well, it's more clear now :)

• easier to read than code with several lines (as long as the line is not too long/convoluted, ofc. And ofc, you need just a bit of practice to know about this kind of construct to read them easlily)
• easier to maintain (well, that shouldn't be needed for that kind of function)
• generally faster than deployed loops (well, doesn't really apply here, unless you're crazy enough to use a for loop when joining the chars ;) ), assuming the behavior of the code is the same
• ...well , that's cooler too. ;)

well, yes, I like the word "well"... x)

That looks nice!
Can someone please explain me why this kind of code is considered as best practice? Is performance better when everything is packed into a single statement? Or just the elegance of the solution? Or both?
I would really like to understand... thanks.