<html>
<head><title>Payment Form</title></head>
<body>
    <p>Payment page</p>
    <form name="input" action="${callback_url}" method="post">
        % for name, value in post_params.items():
        <input type="hidden" name="${name}" value="${value}">
        % endfor
        <input type="submit" value="Submit">
    </form>
</body>
</html>
