package listpkg is
   type List is private; -- A more descriptive name

   procedure clear(l: in out List);
   --  Delete all nodes in list


   procedure makeList(first, last: Natural; l: out List);
   --  Creates a list of integers from first to last


   procedure putList(l: List);
   -- Print the list


   function equal(l, r: List) return Boolean;
   -- Compare entire list, not just pointers l and r


   procedure copy(dest: out List; source: In List);
   --  Make dest point to a deep copy of souce
   --  Current version makes a shallow copy

private
   type Node;
   type List is access Node;
   type Node is record
      val: Natural;
      next: List;
   end record;
end listpkg;