/* This macro will be parsed as PHP code (see http://www.php.net)

The calculateshipping function is called every time a shipping calculation request is made by Shopify.

The function must return an array of available shipping options, otherwise no shipping options will be returned to your customers.
*/
function calculateshipping($DATA) {

    /* do not edit above this line */

    $_RATES = array();

    $productsInCollection = getcollection(1234567890); //where 1234567890 is the colelction id (see user guide for more information)

    $isProductInCollection = false;
    foreach ($DATA['items'] as $item) {
        if (in_array($item['product_id'],$productsInCollection)) {
            $isProductInCollection = true;
        }
    }

    return $_RATES;

    /* do not edit below this line */

}