#!/usr/bin/perl
use strict;
sub screwed {
  my ($in) = @_;
  open(IN, "<$in");
  while(<IN>) { print "file $in contains $_"; }
  close(IN);
}
my @instances = ("a", "b");
map { print "before $_\n" } @instances;
map { screwed "$_"; } @instances;
map { print "after $_\n" } @instances;

##</code><code>##

a1
a2

##</code><code>##

b1
b2

##</code><code>##

before a
before b
file a contains a1
file a contains a2
file b contains b1
file b contains b2
after
after

##</code><code>##

before a
before b
opening file named a
opening file named b
after a
after b