-- This is the generic implementation for a stack abstract data type.

package body StackPkg is

	function IsEmpty (S : Stack) return Boolean is
	begin
		return S.Top = 0;
	end IsEmpty;

	...

	procedure Push (Item : ItemType; S : in out Stack) is
      --  Precondition guarantees that s is not full
	begin
			S.Top := S.Top + 1;
			S.Elements(S.Top) := Item;
	end Push;

	...

end StackPkg;