code: func GetPackageProducts(
  	sess *session.Session,
  	packageId int,
  	mask ...string,
  ) ([]datatypes.Product_Item, error) {
  
  	objectMask := "id,capacity,description,units,keyName,prices[id,locationGroupId,categories[id,name,categoryCode]]"
  	if len(mask) > 0 {
  		objectMask = mask[0]
  	}
  
  	service := services.GetProductPackageService(sess)
  
  	// Get product items for package id
  	return service.
  		Id(packageId).
  		Mask(objectMask).
  		GetItems()
  }
docs: // GetPackageProducts Get a list of product items for a specific product
  // package ID