docs: function (mu, uriString, filename) {
          console.info('#green{[convert file]} ' + filename + ' #green{to data uri]}\n');
          return mu.replace(uriString, [
              'data:',
              mime.getType(filename),
              ';base64,',
              fs.readFileSync(filename).toString('base64')
          ].join(''));
      }