如何默认清除除国家以外的所有WooCommerce结帐字段？

function custom_override_checkout_fields($fields) {
    $billing_fields = $fields['billing'];
    
    // 清除除国家以外的所有结账字段
    foreach ($billing_fields as $key => $field) {
        if ($key !== 'country') {
            unset($billing_fields[$key]);
        }
    }
    
    $fields['billing'] = $billing_fields;
    
    return $fields;
}
add_filter('woocommerce_checkout_fields', 'custom_override_checkout_fields');