code: function (base, res) {
    base.stream('png', function (err, stdout) {
      if (err) {
        throw err;
      }
      res.setHeader('Expires', new Date(Date.now() + 600000));
      res.setHeader('Content-Type', 'image/png');
      stdout.pipe(res);
    });
  }
docs: /*
  Private Methods
   Write stream of image