use warnings;
use strict;
use CGI qw(:standard);
use CGI::Cookie;

my $cookies = CGI::Cookie->fetch;
my $cookie = $cookies->{sessionID} ||
            cookie(-name => 'sessionID',
                   -value => 0,
                  );

$cookie->value( $cookie->value + 1 );

print
    header(-cookie => $cookie),
    start_html(),
    start_form(),
    textfield(-name => "cookie",
              -value => $cookie->value),
    submit(),
    end_form(),
    end_html();