namespace boost {
  namespace text {
    struct grapheme;
    template<code_point_iter I> struct grapheme_ref;
    int storage_code_units(grapheme const &);
    template<code_point_iter I> int storage_code_units(grapheme_ref< I >);
    template<code_point_iter I1, code_point_iter I2> 
      constexpr bool operator==(grapheme_ref< I1 >, grapheme_ref< I2 >);
    template<code_point_iter I1, code_point_iter I2> 
      constexpr bool operator!=(grapheme_ref< I1 >, grapheme_ref< I2 >);
    template<code_point_iter I> 
      constexpr bool operator==(grapheme const &, grapheme_ref< I >);
    template<code_point_iter I> 
      constexpr bool operator==(grapheme_ref< I >, grapheme const &);
    template<code_point_iter I> 
      constexpr bool operator!=(grapheme const &, grapheme_ref< I >);
    template<code_point_iter I> 
      constexpr bool operator!=(grapheme_ref< I >, grapheme const &);
  }
}namespace std {
  namespace ranges {
  }
}