docs: function (evt, callback) {
      var self = this;
  
      var extendedEvent = evt;
  
      var eventExtender = self.tree.getPreEventExtender(self.eventDispatcher.getTargetInformation(evt));
  
      if (!eventExtender) {
        return callback(null, extendedEvent);
      }
  
      eventExtender.extend(extendedEvent, function (err, extEvt) {
        if (err) {
          debug(err);
        }
        extendedEvent = extEvt || extendedEvent;
        callback(err, extendedEvent);
      });
    }