generic
    type Tree is private;
    with function Is_Null (The_Tree : in Tree) return Boolean;
    with function Number_Of_Children_In (The_Tree : in Tree) return Natural;
    with function Child_Of
                     (The_Tree : in Tree; The_Child : in Positive) return Tree;
package Tree_Search_Arbitrary is

    generic
        with procedure Process (The_Tree : in Tree; Continue : out Boolean);
    procedure Traverse_Pre_Order (The_Tree : in Tree);

    generic
        with procedure Process (The_Tree : in Tree; Continue : out Boolean);
    procedure Traverse_Post_Order (The_Tree : in Tree);

end Tree_Search_Arbitrary;