 = (src, used) => {
                return src.replace(/#\s*include\s*[<"](.*?)[>"]/g, function (_, hn) {
                    if (used[hn])
                        return '';
                    used[hn] = true;
                    var h = processInclude(HEADERS[hn], used);
                    if (!h) {
                        throw hn + ": No such file or directory";
                    }
                    return h;
                });
            }

            src = processInclude(src, {});

          