code: func (r Billing_Order_Cart) GetCartByCartKey(cartKey *string) (resp datatypes.Billing_Order_Cart, err error) {
  	params := []interface{}{
  		cartKey,
  	}
  	err = r.Session.DoRequest("SoftLayer_Billing_Order_Cart", "getCartByCartKey", params, &r.Options, &resp)
  	return
  }
docs: // Retrieve a valid cart record of a SoftLayer order.