boost::text::v1::to_title
// In header: <boost/text/case_mapping.hpp> template<code_point_range R, std::weakly_incrementable O, typename NextWordBreakFunc = next_word_break_callable> case_mapping_result< std::ranges::borrowed_iterator_t< R >, O > to_title(R && r, O out, case_language lang = case_language::other, NextWordBreakFunc next_word_break = NextWordBreakFunc{});