  void print_vector(std::ostream& out, const CGAL::Vector_3<R>& v) {
    print_vector_impl(out, Nef_3_internal::get_vector(v), typename Fraction_traits<typename R::FT>::Decompose() );
  }
  void print_vector(std::ostream& out, const CGAL::Vector_3<R>& v) {
    print_vector_impl(out, Nef_3_internal::get_vector(v), typename Fraction_traits<typename R::FT>::Decompose() );
  }