docs: function open(method, url, async, username, password) {
      this.method = method;
      this.url = url;
      this.async = typeof async == "boolean" ? async : true;
      this.username = username;
      this.password = password;
      this.responseText = null;
      this.responseXML = null;
      this.responseURL = url;
      this.requestHeaders = {};
      this.sendFlag = false;
      this._readyStateChange(FakeXMLHttpRequest.OPENED);
    }