  typename EK::Point_3 read_point_impl(std::istream& in, Null_functor) {
    typename K::FT hx, hy, hz, hw;
    in >> hx >> hy >> hz >> hw;
    return typename EK::Point_3(hx,hy,hz,hw);
  }
  typename EK::Point_3 read_point_impl(std::istream& in, Null_functor) {
    typename K::FT hx, hy, hz, hw;
    in >> hx >> hy >> hz >> hw;
    return typename EK::Point_3(hx,hy,hz,hw);
  }