use warnings;
use strict;

##</code><code>##

Unquoted string "test" may clash with future reserved word

##</code><code>##

#!/usr/bin/env perl
use warnings;
use strict;

open my $test_fh, '<', @ARGV or die "Can not open file $!\n";
while (<$test_fh>) {	
	s/th/TH/gi;
	print;
}
close $test_fh;