function wcexics_get_combo_set_form($skuMetaId) {
    $comboset = ComboSet::getComboSetBySkuMetaId($skuMetaId);
    if ($comboset instanceof GenericError) {
        return '';
    }

    $groups = $comboset->getGroups();
    if (empty($groups)) {
        return '';
    }

    $html = '';
    foreach ($groups as $group) {
        $html .= wcexics_get_group_form($group);
    }

    $contents = $html;
    if (!empty($contents)) {
        // wrap with grid container
        $html = '<div class="wcexics combo-set-form" id="combo-set_' . $comboset->getId() . '">';
        $html .= $contents;
        $html .= '</div>';
    }

    return $html;
}