namespace boost {
  namespace text {
    namespace v1 {
      template<code_point_iter I, std::sentinel_for< I > S> 
        std::size_t estimated_width_of_graphemes(I, S);
      template<code_point_range R> 
        std::size_t estimated_width_of_graphemes(R &&);
      template<typename CPIter, typename Sentinel> 
        auto estimated_width_of_graphemes(CPIter first, Sentinel last);
      template<typename CPRange> 
        auto estimated_width_of_graphemes(CPRange && r);
    }
  }
}