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declare
   L : List;
   C : Cursor;
begin
   L.Append (New_Item => E);
   C := L.Last;
   E2 := Element (Position => C);
   Replace_Element (Position => C, By => E3);
   L.Insert (Before => C, New_Item => E4);
   L.Delete (Position => C);
   L.Delete_Last;
end;