public function addonButton($label, $options = [])
    {
        $attributes = array_merge(['class' => 'btn', 'type' => 'button'], $options);

        if (isset($options['class'])) {
            $attributes['class'] .= ' btn';
        }

        return '<div class="input-group-btn"><button ' . $this->html->attributes($attributes) . '>'.$label.'</button></div>';
    }