code: function _fireCallback(callback, e, combo, sequence) {
  
              // if this event should not happen stop here
              if (self.stopCallback(e, e.target || e.srcElement, combo, sequence)) {
                  return;
              }
  
              if (callback(e, combo) === false) {
                  _preventDefault(e);
                  _stopPropagation(e);
              }
          }
docs: actually calls the callback function
  
  if your callback function returns false this will use the jquery
  convention - prevent default and stop propogation on the event
  
  @param {Function} callback
  @param {Event} e
  @returns void