code: function setCookie (res, name, val, options) {
    var data = Cookie.serialize(name, val, options)
  
    var prev = res.getHeader('set-cookie') || []
    var header = Array.isArray(prev) ? prev.concat(data)
      : [prev, data]
  
    res.setHeader('set-cookie', header)
  }
docs: Set a cookie on the HTTP response.
  
  @param {OutgoingMessage} res
  @param {string} name
  @param {string} val
  @param {Object} [options]
  @api private