#!/usr/local/bin/perl

  use strict;

  my $foo = 1;
  my $fum = 1;

  print STDERR "variables are now: $foo $fum\n";

  foo($foo, $fum);

  my $foo = 2;
     $fum = 2;

  print STDERR "variables are now: $foo $fum\n";

sub foo {
  my $foo = shift;
  my $fum = shift;

  print STDERR "variables are now: $foo $fum\n";
}