  void extract_regularization()
  /*{\Xop converts |\Mvar| to its regularization. }*/
  { CGAL_NEF_TRACEN("extract regularization");
    extract_interior();
    extract_closure();
  }
  void extract_regularization()
   
  { CGAL_NEF_TRACEN("extract regularization");
    extract_interior();
    extract_closure();
  }