use strict;
use warnings;
use File::Spec::Functions "devnull";

sub bar {
  open my $fh, "< $_[0]" or die "couldn't open $_[0]: $!";
  print while <$fh>;
}

sub foo { for (@_) { bar(devnull()) } }

$. = 0;
foo($.);

##</code><code>##

use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Terse=1;

sub foo {
   print "foo: bad args: ", Dumper \@_
      if @_ != 2 || $_[0] !~ /^[tf]/ || $_[1] !~ /statement/;

   my ($tf, $statement) = @_;

   if ($tf =~ /^t/) {  # Line 12
      print "true: $statement\n";
   } else {
      print "false: $statement\n"
   }
}

for my $statement ("the following statement is true",
                   "the preceding statement is false") {
   $statement =~ /\b(t|f|true|false)\b/ or next;
   foo($1, $statement);
}

##</code><code>##

   foo(0+$.);
   # and
   foo("$1", $statement);