docs: function _readyStateChange(state) {
              this.readyState = state;
  
              if (typeof this.onreadystatechange == "function") {
                  this.onreadystatechange();
              }
  
              this.dispatchEvent(new HttpRequestEvent("readystatechange"));
  
              if (this.readyState == IsotropyXMLHttpRequest.DONE) {
                  this.dispatchEvent(new HttpRequestEvent("load", false, false, this));
                  this.dispatchEvent(new HttpRequestEvent("loadend", false, false, this));
              }
          }