docs: function(moduleRegex) {
          var self = this;
  
          moduleRegex = moduleRegex || /^(.+)\.js$/;
  
          return function(req, res, next) {
              var match = req.url.match(moduleRegex);
              if(!match) return next();
  
              var module= match[1];
  
              self.bundle(module, function(err, src) {
                  res.setHeader('Content-Type', 'text/javascript; charset=utf-8');
                  res.setHeader('Cache-Control', 'no-cache');
  
                  // expose event to allow for custom headers
                  self.emit('pre-response', err, res, module, src);
  
                  res.send(src);
              });
          };
      }