code: func (r Billing_Order_Item) GetStorageGroups() (resp []datatypes.Configuration_Storage_Group_Order, err error) {
  	err = r.Session.DoRequest("SoftLayer_Billing_Order_Item", "getStorageGroups", nil, &r.Options, &resp)
  	return
  }
docs: // Retrieve The drive storage groups that are attached to this billing order item.