A.18.12 The Generic Package Containers.Indefinite_Doubly_Linked_Lists
The language-defined generic package Containers.Indefinite_Doubly_Linked_Lists 
provides private types List and Cursor, and a set of operations for each 
type. It provides the same operations as the package Containers.Doubly_Linked_Lists 
(see 
A.18.3), with the difference that the 
generic formal Element_Type is indefinite. 
 
Static Semantics
The declaration of 
the generic library package Containers.Indefinite_Doubly_Linked_Lists
 
has the same contents and semantics as Containers.Doubly_Linked_Lists 
except:
 
The generic formal Element_Type is indefinite.
The procedure with 
the profile: 
procedure Insert (Container : in out List;
                  Before    : in     Cursor;
                  Position  :    out Cursor;
                  Count     : in     Count_Type := 1);
is omitted.
The actual Element parameter of access subprogram 
Process of Update_Element may be constrained even if Element_Type is 
unconstrained.
The operations Append, Insert, Prepend, and Replace_Element 
that have a formal parameter of type Element_Type perform indefinite 
insertion (see 
A.18). 
 
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