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 ...

I 'm a big fan of Python for data analysis, but even I get curious about what else is available. R has long been the go-to language for statistics, but the "Tidyverse" has given the language a serious ...