$def with (form)
<form action="/" method="get">

$if not form.valid: <p class="error">Please enter in a <a href="http://en.wikipedia.org/wiki/Uniform_Resource_Identifier">URI</a> to shrink</p>

    <fieldset>
        $:form.render()
    </fieldset>

    <input type="submit" value="surink!" />

</form>