static void fn_node_string_substring_build_multi_function(
    blender::nodes::NodeMultiFunctionBuilder &builder)
{
  static blender::fn::CustomMF_SI_SI_SI_SO<std::string, int, int, std::string> substring_fn{
      "Substring", [](const std::string &str, int a, int b) {
        using namespace boost::locale::boundary;
        boost::locale::generator gen;
        std::string output;
        std::string locale = "en_EN.UTF-8";
        // Create mapping of text for token iterator using global locale.
        ssegment_index map(word, locale.begin(), locale.end(), gen(locale));
        // Print all "words" -- chunks of word boundary
        for (ssegment_index::iterator it = map.begin(), e = map.end(); it != e; ++it) {
          output += *it;
        }
        return std::move(output);
      }};
  builder.set_matching_fn(&substring_fn);
}