The class Identity_policy_2<DG,AT> provides a model for the AdaptationPolicy_2 concept. The first template parameter of the Identity_policy_2<DG,AT> class must be a model of the DelaunayGraph_2 concept, whereas as the second template parameter must be a model of the AdaptationTraits_2 concept. This policy rejects no edge and no face of the Delaunay graph, thus giving a Voronoi diagram which is the true dual of the triangulation Delaunay graph. The Voronoi diagram created with this adaptation policy may have degenerate features, such as Voronoi edges of zero length, or Voronoi faces of zero area. This policy assumes that the Delaunay graph, that is adapted, allows for site insertions through an insert method that takes as argument an object of type AT::Site_2. The site inserter functor provided by this policy uses the aforementioned insert method.