package builtin import "errors" var ( ErrCannotAddNegativeOrZeroItem = errors.New("cannot add items with negative quantities or zero") ErrItemNotExist = errors.New("item not exist") ErrItemInsufficientQuantity = errors.New("item insufficient quantity") ErrItemContainerIsFull = errors.New("item container is full") ErrItemContainerNotExist = errors.New("item container not exist") )