use Module::Foo;

my $foo = Module::Foo->new();

$foo->do_something();

##</code><code>##

print header,
    start_html(
        -title   => 'Decimal to Hex Converter',
        -bgcolor => 'black',
        -text    => 'white',
    ),
    h1({align=>'center'},'Decimal to Hex Converter'),
;

##</code><code>##

my $cgi  = CGI->new;
my $tmpl = HTML::Template->new(
    filehandle => \*DATA,
    associate  => $cgi,
);

print $cgi->header, $tmpl->output;

__DATA__
<html>
yadda ...