But in many cases, it doesn’t have to be an either/or proposition. Properly optimized, Python applications can run with surprising speed — perhaps not Java or C fast, but fast enough for Web ...

If the argument is an expression (formula) it will evaluate it first. I don't do python3, but i imagine the python 2 "print x, y" command corresponds to "python (x,y)" if you want to think of it that ...