if ( $show_banner == 1 ) {
    print STDERR "$app_name $version ($app_www)\n";
    print STDERR "$copyright $author, $author_email\n\n";
}

##</code><code>##

use Tie::Trace qw( watch );

my $show_banner = 1;
watch $show_banner;

##</code><code>##

main:: $show_banner => 0 at ./colordiff.pl line 156.