code: function FetchLongPollingTransport(fetch) {
    var _super = new LongPollingTransport()
    var that = Transport.derive(_super)
  
    /**
     * Implements transport via fetch() API
     * @param {Object} packet
     */
    that.xhrSend = function (packet) {
      fetch(packet.url, {
        method: 'post',
        body: packet.body,
        headers: Object.assign(packet.headers, {
          'Content-Type': 'application/json;charset=UTF-8'
        })
      })
      .then(function (response) {
        return response.json()
      })
      .then(packet.onSuccess)
      .catch(packet.onError)
    }
  
    return that
  }
docs: Implements LongPollingTransport using fetch() API
  @access private
  @param {Function} fetch
  @return {FetchLongPollingTransport}