Method get_arg

extlibs/fmt/include/fmt/format.h:2229–2231

  using format_arg = typename Context::format_arg;

  FMT_CONSTEXPR format_arg get_arg(auto_id) {
    return internal::get_arg(context_, parse_context_.next_arg_id());
  }

  FMT_CONSTEXPR format_arg get_arg(int arg_id) {
    parse_context_.check_arg_id(arg_id);