Method yellow

tutorials/verify/verify.h:181–184

      else           return str;
    }
    std::string yellow(std::string str) {
      if (usecolors) return "\033[33m" + str + "\033[0m";
      else           return str;
    }
    std::string red(std::string str) {
      if (usecolors) return "\033[31m" + str + "\033[0m";
      else           return str;