/**
* Add Address to the stack
* @param USPSAddress object $data
* @param string $id the address unique id
* @return void
*/
public function addAddress(USPSAddress $data, $id = null)
{
$packageId = $id !== null ? $id : count($this->addresses) + 1;
$this->addresses['Address'][] = array_merge(array('@attributes' => array('ID' => $packageId)), $data->getAddressInfo());
}
