with Ada.Containers.Doubly_Linked_Lists;
 generic
    type Element_Type is private;
 package Generic_Fifo is
    type Fifo_Type is tagged private;
    procedure Push(The_Fifo : in out Fifo_Type; Item : in Element_Type);
    procedure Pop(The_Fifo : in out Fifo_Type; Item : out Element_Type);
    Empty_Error : Exception;
 private
    package List_Pkg is new Ada.Containers.Doubly_Linked_Lists(Element_Type);
    use List_Pkg;
    Type Fifo_Type is new List with null record;
 end Generic_Fifo;