In Python you would think that functions are the equivalent to subroutines in Perl. Then I realise that it is possible to have nested functions in Python, however not nested subroutines in Perl. What differences are there to consider here? Obviously the way variables are defined in critical. Is there really any difference between (1) having a call to a subroutine and then within a nested loop having a call to another subroutine. And (2) that we see in Python. It was this video that promoted my thinking on this.