code: function plugin(opts) {
      return function(files, metalsmith, done) {
          async.eachSeries(Object.keys(files), prerender, done);
  
          function prerender(file, done) {
              var data = files[file];
              if (!data.mathjax) {
                  done();
              } else {
                  debug("Found mathjax in", file);
                  var contents = data.contents.toString('utf8');
  
                  mjAPI.mjpage(contents, {format: ["TeX"]}, {svg: true}, function(result) {
                      // window.document.body.innerHTML = result.html;
                      // var HTML = "<!DOCTYPE html>\n" + window.document.documentElement.outerHTML.replace(/^(\n|\s)*/, "");
                      data.contents = new Buffer(result);
                      debug('Prerendered MathJAX for file: %s', file);
                      done();
                  });
              }
          };
      };
  }
docs: Metalsmith plugin to hide drafts from the output.
  
  @return {Function}