if ($checks{'data'} =~ /([^$checks{'regex'}])/) {
    bail_out("Bad input.");
}

##</code><code>##

if (defined $checks{'value'}) {
	if (ref $checks{'value'} eq 'Regexp') {
		bail_out("Bad input.")
			unless ($checks{'data'} =~ $checks{'value'});
	} else {
		bail_out("Bad input.")
			unless ($checks{'data'} eq $checks{'value'});
	}
}

##</code><code>##

$email_address = sanitize(
  data        => param('email'),
  field       => 'Email address',
  obligatory  => 1,
  min         => 9,
  value       => qr/^[a-zA-Z0-9\.]+\@[a-zA-Z0-9\.]+$/,
);
$color = sanitize(
  data        => param('color'),
  field       => 'Color',
  obligatory  => 1,
  min         => 3,
  max         => 4,
  value       => qr/^(?:red|green|blue)$/,
);

##</code><code>##

$username = sanitize(
  data        => param('username'),
  field       => 'Username',
  obligatory  => 1,
  min         => 8,
  max         => 8,
  value       => qr/^[%;&()#\w ]+$/,
);

##</code><code>##

$autosave = sanitize(
  data        => param('autosave'),
  field       => 'Autosave',
  obligatory  => 0,
  max         => 2,
  value       => 'on', # not a regular expression; $checks{'data'} must eq "on"
);