code: function setHeaders (res, headers) {
    if (!headers) {
      return
    }
  
    var keys = Object.keys(headers)
    for (var i = 0; i < keys.length; i++) {
      var key = keys[i]
      res.setHeader(key, headers[key])
    }
  }
docs: Set response headers from an object.
  
  @param {OutgoingMessage} res
  @param {object} headers
  @private