code: function streamFile(res, fileName, status, contentType, prefix, suffix) {
      res.statusCode = status || 200;
      res.setHeader('Content-Type', contentType);
      if (prefix) {
          res.write(prefix);
      }
  
      var s = fs.createReadStream('templates/' + fileName, {encoding: 'utf8'});
      s.on('readable', getReadableHandler(s, res));
      s.on('end', function() {
          if (suffix) {
              res.write(suffix);
          }
          res.end();
      });
  }
docs: In this example, I'm streaming contents of files on disk to the client,
  but this can be replaced with any kind of streaming content (a templating library
  used to construct HTML pages, for example)
  fileName - name of the file to stream
  prefix - content to prepend before file contents
  suffix - content to append after file contents